Wirelessly powered audio devices

ABSTRACT

Techniques herein provide wireless energy transfer to audio devices such as headphones, headsets, hearing aids, and the like. Audio devices are integrated with a device resonator. The device resonator may be positioned and oriented to reduce interaction with lossy or sensitive components of the audio device. A repeater resonator and/or a source resonator is integrated into a headrest of a seat or a chair providing continuous power to the headphones while in use. The audio devices may be recharged wirelessly when positioned near source resonators that may be embedded in pads, tables, carrying cases, cups, and the like.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. patent applicationSer. No. 12/650,916 filed Dec. 31, 2009. U.S. patent application Ser.No. 12/650,916 filed Dec. 31, 2009 is a continuation-in-part of U.S.patent application Ser. No. 12/567,716 filed Sep. 25, 2009 (now U.S.Pat. No. 8,461,719, issued Jun. 11, 2013) which claims the benefit ofthe following U.S. Provisional patent applications: U.S. App. No.61/100,721 filed Sep. 27, 2008; U.S. App. No. 61/108,743 filed Oct. 27,2008; U.S. App. No. 61/147,386 filed Jan. 26, 2009; U.S. App. No.61/152,086 filed Feb. 12, 2009; U.S. App. No. 61/178,508 filed May 15,2009; U.S. App. No. 61/182,768 filed Jun. 1, 2009; U.S. App. No.61/121,159 filed Dec. 9, 2008; U.S. App. No. 61/142,977 filed Jan. 7,2009; U.S. App. No. 61/142,885 filed Jan. 6, 2009; U.S. App. No.61/142,796 filed Jan. 6, 2009; U.S. App. No. 61/142,889 filed Jan. 6,2009; U.S. App. No. 61/142,880 filed Jan. 6, 2009; U.S. App. No.61/142,818 filed Jan. 6, 2009; U.S. App. No. 61/142,887 filed Jan. 6,2009; U.S. App. No. 61/156,764 filed Mar. 2, 2009; U.S. App. No.61/143,058 filed Jan. 7, 2009; U.S. App. No. 61/152,390 filed Feb. 13,2009; U.S. App. No. 61/163,695 filed Mar. 26, 2009; U.S. App. No.61/172,633 filed 24, 2009; U.S. App. No. 61/169,240 filed Apr. 14, 2009,U.S. App. No. 61/173,747 filed Apr. 29, 2009.

This application also claims the benefit of priority to U.S. ProvisionalPatent Application No. 61/714,996 filed Oct. 17, 2012 titled “Wirelessheadphones” and to U.S. Provisional Patent Application No. 61/825,942filed May 21, 2013 titled “Wirelessly powered hearing aid”.

Each of the foregoing applications are incorporated herein by referencein their entirety

BACKGROUND

This disclosure relates to wireless energy transfer, methods, systemsand apparati to accomplish such transfer, and applications.

Audio devices such as headphones, personal speakers, headsets, and thelike require electrical energy to produce an audio output or providenoise cancellation. The electrical energy for such devices is usuallydelivered from disposable batteries and/or a wired connection to anenergy source such as a stereo, mobile device, or a music player.Existing methods reduce the utility, comfort, and convenience of theaudio devices for many applications. Headphones, for example, are wornon the user's head or neck area which often limits the weight and/orsize of the devices and may limit the size of the batteries that may becomfortably tolerated by the user. Smaller batteries result in shorteruse windows or frequent replacement and/or recharging of the batteries.Cables that tether the audio devices to power sources may limit themobility of the audio devices and may pose a tangling hazard and limitthe reliability of the audio devices. These limitations are magnifiedwhen considering venues and or environments for which hundreds orthousands of person-worn devices are worn or used. Theaters, airplanes,work environments, and the like, that may rely on person audio devicesmay need to accommodate battery supplies and chargers for the devicesand/or mitigate the consequences of reduced mobility and reliability dueto cables. Methods that reduce or eliminate the need for batteries orcabled sources for energy would increase the utility and convenience ofthe devices in many applications.

In addition to the audio devices described above, wireless energytransfer may be used to recharge the batteries of small audio deviceswithout having to remove the batteries. BlueTooth® and headsets maybenefit from this technology because the connected used to recharge thebatteries using a wired solution may be eliminated, making the headsetsmore compact and allowing for new designs that are unconstrained by thepresence of the electrical connector. In addition, hearing aids may berecharged by simply placing them on a charging mat or in a charging bowlor enclosure or region. Wireless recharging may eliminate the need foran accessible battery compartment in the hearing aid, which will make iteasier for uses to keep the devices charged and may also make it easierto clean and maintain the devices.

SUMMARY

Techniques herein attempt to provide wireless energy transfer to audiodevices such as headphones, headsets, and the like. In some embodiments,audio devices are integrated with a device resonator. The deviceresonator may be positioned and oriented to reduce interaction withlossy or sensitive components of the audio device. In an example ofheadphones, a repeater resonator and/or a source resonator may beintegrated into a headrest of a seat or a chair providing continuouspower to the headphones while in use. In other embodiments, the audiodevices may be recharged wirelessly when positioned near sourceresonators that may be embedded in pads, tables, carrying cases, cups,and the like.

In embodiments a wirelessly powered audio device includes an audiooutput element; the audio output element may be configured to generatesounds audible by a user. The audio device may further include a deviceresonator structure wherein the device resonator structure may beconfigured to wirelessly receive energy via oscillating magnetic fields.In some embodiments the device resonator may be configured to reduce theinteraction of the magnetic fields with the audio output element. Apower demand monitor may also be included. The power demand monitor maybe configured to monitor the power demands of the audio device and thepower received via the device resonator structure and to cause the audiooutput element to generate an audible signal when the power demands ofthe audio device exceed the power delivered by the device resonator. Insome embodiments the device resonator may be positioned near the audiooutput element such that the device resonator has a relatively highperturbed-Q. In the embodiments where the audio output element includesa solenoid coil, the resonator may be positioned such that the dipolemoment of the resonator structure is orthogonal to the dipole moment ofthe solenoid. In some embodiments magnetic material and/or electricalconductors may be used to shield the audio output element from themagnetic fields near the device resonator structure. The audio devicemay also include rechargeable batteries and the energy captured by thedevice resonator may be used to recharge the batteries.

In some embodiments a method for wirelessly powering of an audio deviceincludes the step of initiating wireless energy transfer from a wirelessenergy source. The method further includes monitoring, using a powerdemand monitor, a power demand of the audio device and monitoring, usinga noise monitor, the noise of an audio signal due to the wireless energytransfer. Based on the power demands, energy transfer may be adjusted toa minimum level that satisfies the power demand of the audio device. Thenoise of the audio signal may be filtered.

BRIEF DESCRIPTION OF FIGURES

FIG. 1 is a system block diagram of wireless energy transferconfigurations.

FIGS. 2A-2F are exemplary structures and schematics of simple resonatorstructures.

FIG. 3 is a block diagram of a wireless source with a single-endedamplifier.

FIG. 4 is a block diagram of a wireless source with a differentialamplifier.

FIGS. 5A and 5B are block diagrams of sensing circuits.

FIGS. 6A, 6B, and 6C are block diagrams of a wireless source.

FIGS. 7A-B are diagram showing two resonator configurations withrepeater resonators.

FIGS. 8A-B are diagram showing two resonator configurations withrepeater resonators.

FIG. 9A is a diagram showing a configuration with two repeaterresonators 9B is a diagram showing a resonator configuration with adevice resonator acting as a repeater resonator.

FIG. 10 is a diagram of a system utilizing a repeater resonator with adesk environment.

FIG. 11 is a diagram of a system utilizing a resonator that may beoperated in multiple modes.

FIG. 12 is a circuit block diagram of the power and control circuitry ofa resonator configured to have multiple modes of operation.

FIG. 13 is a diagram of an embodiment of a system with wirelesslypowered audio devices.

FIG. 14 is a diagram of an embodiment of a system with wirelesslypowered audio devices.

FIG. 15 is a diagram of an embodiment of headphones configured forwirelessly powered.

FIG. 16 is an exploded view of an embodiment of headphones configured toreceive wireless power.

FIG. 17 is a diagram of a device resonator coil configured to fit into acup of a headphone.

FIG. 18 is a block diagram of a wirelessly powered audio device.

FIG. 19 is diagram of a process for controlling wireless energy transferin an audio device.

FIG. 20 is a diagram of a charging configuration.

FIG. 21 is a diagram of a wireless hands free headset configured forwireless energy transfer.

FIG. 22 is a diagram of a charging configuration.

FIG. 23 is a diagram of a device resonator coil configured for a handsfree headset.

FIG. 24 is a diagram of a source resonator coil.

FIG. 25 is a block diagram of a wirelessly powered hearing aid system.

FIG. 26 is a diagram of an embodiment of a device resonator and a sourceresonator.

FIG. 27 is a block diagram of a wirelessly powered hearing aid system.

FIG. 28A is a graph showing coil-to-coil efficiency (%) as the sourcecoil size is varied. FIG. 28B is a graph showing coupling factor, k, asthe source coil size is varied.

DETAILED DESCRIPTION

Audio devices may be powered and/or recharged wirelessly. Audio devicessuch as headphones, headsets, hands free headsets, phone headsets,and/or other audio devices may be wirelessly powered while worn or usedby the user. In some embodiments, the audio devices may be wirelesslyrecharged and/or powered when not in use, when stored or positioned orplaced in a holder, carrying case, basket, and/or the like.

Audio devices that are wirelessly powered and/or charged may, in manyembodiments, be completely wireless with both data (i.e. music or otheraudio data) and power transmitted wirelessly. Data may be transmittedusing wireless data transmission protocols such as Bluetooth, WiFi, FM,Infrared, and/or other protocols and technologies. Power may betransmitted to the devices via highly coupled resonant wireless energytransfer.

Resonators, configured for wireless energy transfer may be integrated orattached to the audio devices. The resonators may receive energy viaoscillating magnetic fields from source and/or repeater resonators thatmay be embedded or attached to furniture, televisions, monitors, walls,ceilings, chairs, and the like. For example, one example embodiment of asystem with wirelessly powered headphones is shown in FIG. 13. Thefigure shows a system in which a pair of headphones 1304 worn by a user1306 may be wirelessly powered and/or charged while in use by the user.The user may wear the headphones while the headphones wirelessly receiveaudio data and energy. In the example embodiment a source resonator1310, generating an oscillating magnetic field may be attached orintegrated into the headrest 1302 of the chair. The oscillating magneticfields may be captured by one or more device resonators 1308 that areattached and/or integrated into the headphone devices. The energy storedin the oscillating magnetic field may be transformed into electricalenergy and used to power the headphones and/or charge the internalbatteries of the device. The headphones may therefore be usedindefinitely without wires or the need to replace batteries. Likewise,the headphones may not require any wires or cables that may inhibitmovement or mobility. Such headphones may not need any electricalconnectors or connections which may be failure prone and may reduce theusability and/or lifetime of the headphones.

The ability to indefinitely power a set of headphones may be betterappreciated when considering use environments such as airplanes, forexample. Headphones are an integral part of an airplane's entertainmentsystem that keeps passengers occupied and entertained on long flights.Traditional battery operated headphones may not be practical since thebatteries of such devices may need to be replaced for every flight.Wired headphones, while less expensive, may cause a potential safetyproblem. In an emergency, passengers may need to disembark the airplaneas quickly as possible with many of the passengers having to scoot ormake their way through a row of seats to get to an aisle. Wiredheadphones left by passengers may create a dangerous tangle of wires andtrap panicked passengers, for example. The safety and practical concernsmay be solved by the embodiments of the invention described herein.Source and/or repeater resonators may be integrated into the seats,ceilings, walls, floor, windows, and the like of the airplane. Thesource and repeater resonators may generate oscillating magnetic fieldsthat may be captured by the resonators attached or embedded to theheadphones allowing the headphones to be powered wirelessly, without apotential tangle of wires.

The devices, methods, and systems that may be used to enable wirelessenergy transfer to audio devices such as headphones are describedherein.

Wireless Energy Transfer

Wireless energy transfer systems described herein may be implementedusing a wide variety of resonators and resonant objects.

As those skilled in the art will recognize, important considerations forresonator-based power transfer include resonator efficiency andresonator coupling. Extensive discussion of such issues, e.g., coupledmode theory (CMT), coupling coefficients and factors, quality factors(also referred to as Q-factors), and impedance matching is provided, forexample, in U.S. patent application Ser. No. 12/789,611 published onSep. 23, 2010 as US 20100237709 and entitled “RESONATOR ARRAYS FORWIRELESS ENERGY TRANSFER,” and U.S. patent application Ser. No.12/722,050 published on Jul. 22, 2010 as US 20100181843 and entitled“WIRELESS ENERGY TRANSFER FOR REFRIGERATOR APPLICATION” and incorporatedherein by reference in its entirety as if fully set forth herein.

A resonator may be defined as a resonant structure that can store energyin at least two different forms, and where the stored energy oscillatesbetween the two forms. The resonant structure will have a specificoscillation mode with a resonant (modal) frequency, f, and a resonant(modal) field. The angular resonant frequency, ω, may be defined asω=2πf, the resonant period, T, may be defined as T=1/f=2π/ω, and theresonant wavelength, λ, may be defined as λ=c/f, where c is the speed ofthe associated field waves (light, for electromagnetic resonators). Inthe absence of loss mechanisms, coupling mechanisms or external energysupplying or draining mechanisms, the total amount of energy stored bythe resonator, W, would stay fixed, but the form of the energy wouldoscillate between the two forms supported by the resonator, wherein oneform would be maximum when the other is minimum and vice versa.

For example, a resonator may be constructed such that the two forms ofstored energy are magnetic energy and electric energy. Further, theresonator may be constructed such that the electric energy stored by theelectric field is primarily confined within the structure while themagnetic energy stored by the magnetic field is primarily in the regionsurrounding the resonator. In other words, the total electric andmagnetic energies would be equal, but their localization would bedifferent. Using such structures, energy exchange between at least twostructures may be mediated by the resonant magnetic near-field of the atleast two resonators. These types of resonators may be referred to asmagnetic resonators.

An important parameter of resonators used in wireless power transmissionsystems is the Quality Factor, or Q-factor, or Q, of the resonator,which characterizes the energy decay and is inversely proportional toenergy losses of the resonator. It may be defined as Q=ω*W/P, where P isthe time-averaged power lost at steady state. That is, a resonator witha high-Q has relatively low intrinsic losses and can store energy for arelatively long time. Since the resonator loses energy at its intrinsicdecay rate, 2Γ, its Q, also referred to as its intrinsic Q, is given byQ=ω2Γ. The quality factor also represents the number of oscillationperiods, T, it takes for the energy in the resonator to decay by afactor of e^(−2π). Note that the quality factor or intrinsic qualityfactor or Q of the resonator is that due only to intrinsic lossmechanisms. The Q of a resonator connected to, or coupled to a powergenerator, g, or load, l, may be called the “loaded quality factor” orthe “loaded Q”. The Q of a resonator in the presence of an extraneousobject that is not intended to be part of the energy transfer system maybe called the “perturbed quality factor” or the “perturbed Q”.

Resonators, coupled through any portion of their near-fields mayinteract and exchange energy. The efficiency of this energy transfer canbe significantly enhanced if the resonators operate at substantially thesame resonant frequency. By way of example, but not limitation, imaginea source resonator with Q_(s) and a device resonator with Q_(d). High-Qwireless energy transfer systems may utilize resonators that are high-Q.The Q of each resonator may be high. The geometric mean of the resonator

${Q^{\prime}s},\sqrt{\sqrt{Q_{s}Q_{d}}}$may also or instead be high.

The coupling factor, k, is a number between 0≦|k|≦1, and it may beindependent (or nearly independent) of the resonant frequencies of thesource and device resonators, when those are placed at sub-wavelengthdistances. Rather the coupling factor k may be determined mostly by therelative geometry and the distance between the source and deviceresonators where the physical decay-law of the field mediating theircoupling is taken into account. The coupling coefficient used in CMT,κ=k√{square root over (ω_(s)ω_(d))}/2, may be a strong function of theresonant frequencies, as well as other properties of the resonatorstructures. In applications for wireless energy transfer utilizing thenear-fields of the resonators, it is desirable to have the size of theresonator be much smaller than the resonant wavelength, so that powerlost by radiation is reduced. In some embodiments, high-Q resonators aresub-wavelength structures. In some electromagnetic embodiments, high-Qresonator structures are designed to have resonant frequencies higherthan 100 kHz. In other embodiments, the resonant frequencies may be lessthan 1 GHz.

In exemplary embodiments, the power radiated into the far-field by thesesub wavelength resonators may be further reduced by lowering theresonant frequency of the resonators and the operating frequency of thesystem. In other embodiments, the far field radiation may be reduced byarranging for the far fields of two or more resonators to interferedestructively in the far field.

In a wireless energy transfer system a resonator may be used as awireless energy source, a wireless energy capture device, a repeater ora combination thereof. In embodiments a resonator may alternate betweentransferring energy, receiving energy or relaying energy. In a wirelessenergy transfer system one or more magnetic resonators may be coupled toan energy source and be energized to produce an oscillating magneticnear-field. Other resonators that are within the oscillating magneticnear-fields may capture these fields and convert the energy intoelectrical energy that may be used to power or charge a load therebyenabling wireless transfer of useful energy.

The so-called “useful” energy in a useful energy exchange is the energyor power that must be delivered to a device in order to power or chargeit at an acceptable rate. The transfer efficiency that corresponds to auseful energy exchange may be system or application-dependent. Forexample, high power vehicle charging applications that transferkilowatts of power may need to be at least 80% efficient in order tosupply useful amounts of power resulting in a useful energy exchangesufficient to recharge a vehicle battery without significantly heatingup various components of the transfer system. In some consumerelectronics applications, a useful energy exchange may include anyenergy transfer efficiencies greater than 10%, or any other amountacceptable to keep rechargeable batteries “topped off” and running forlong periods of time. In implanted medical device applications, a usefulenergy exchange may be any exchange that does not harm the patient butthat extends the life of a battery or wakes up a sensor or monitor orstimulator. In such applications, 100 mW of power or less may be useful.In distributed sensing applications, power transfer of microwatts may beuseful, and transfer efficiencies may be well below 1%.

A useful energy exchange for wireless energy transfer in a powering orrecharging application may be efficient, highly efficient, or efficientenough, as long as the wasted energy levels, heat dissipation, andassociated field strengths are within tolerable limits and are balancedappropriately with related factors such as cost, weight, size, and thelike.

The resonators may be referred to as source resonators, deviceresonators, first resonators, second resonators, repeater resonators,and the like. Implementations may include three (3) or more resonators.For example, a single source resonator may transfer energy to multipledevice resonators or multiple devices. Energy may be transferred from afirst device to a second, and then from the second device to the third,and so forth. Multiple sources may transfer energy to a single device orto multiple devices connected to a single device resonator or tomultiple devices connected to multiple device resonators. Resonators mayserve alternately or simultaneously as sources, devices, and/or they maybe used to relay power from a source in one location to a device inanother location. Intermediate electromagnetic resonators may be used toextend the distance range of wireless energy transfer systems and/or togenerate areas of concentrated magnetic near-fields. Multiple resonatorsmay be daisy-chained together, exchanging energy over extended distancesand with a wide range of sources and devices. For example, a sourceresonator may transfer power to a device resonator via several repeaterresonators. Energy from a source may be transferred to a first repeaterresonator, the first repeater resonator may transfer the power to asecond repeater resonator and the second to a third and so on until thefinal repeater resonator transfers its energy to a device resonator. Inthis respect the range or distance of wireless energy transfer may beextended and/or tailored by adding repeater resonators. High powerlevels may be split between multiple sources, transferred to multipledevices and recombined at a distant location.

The resonators may be designed using coupled mode theory models, circuitmodels, electromagnetic field models, and the like. The resonators maybe designed to have tunable characteristic sizes. The resonators may bedesigned to handle different power levels. In exemplary embodiments,high power resonators may require larger conductors and higher currentor voltage rated components than lower power resonators.

FIG. 1 shows a diagram of exemplary configurations and arrangements of awireless energy transfer system. A wireless energy transfer system mayinclude at least one source resonator (R1) 104 (optionally R6, 112)coupled to an energy source 102 and optionally a sensor and control unit108. The energy source may be a source of any type of energy capable ofbeing converted into electrical energy that may be used to drive thesource resonator 104. The energy source may be a battery, a solar panel,the electrical mains, a wind or water turbine, an electromagneticresonator, a generator, and the like. The electrical energy used todrive the magnetic resonator is converted into oscillating magneticfields by the resonator. The oscillating magnetic fields may be capturedby other resonators which may be device resonators (R2) 106, (R3) 116that are optionally coupled to an energy drain 110. The oscillatingfields may be optionally coupled to repeater resonators (R4, R5) thatare configured to extend or tailor the wireless energy transfer region.Device resonators may capture the magnetic fields in the vicinity ofsource resonator(s), repeater resonators and other device resonators andconvert them into electrical energy that may be used by an energy drain.The energy drain 110 may be an electrical, electronic, mechanical orchemical device and the like configured to receive electrical energy.Repeater resonators may capture magnetic fields in the vicinity ofsource, device and repeater resonator(s) and may pass the energy on toother resonators.

A wireless energy transfer system may comprise a single source resonator104 coupled to an energy source 102 and a single device resonator 106coupled to an energy drain 110. In embodiments a wireless energytransfer system may comprise multiple source resonators coupled to oneor more energy sources and may comprise multiple device resonatorscoupled to one or more energy drains.

In embodiments the energy may be transferred directly between a sourceresonator 104 and a device resonator 106. In other embodiments theenergy may be transferred from one or more source resonators 104, 112 toone or more device resonators 106, 116 via any number of intermediateresonators which may be device resonators, source resonators, repeaterresonators, and the like. Energy may be transferred via a network orarrangement of resonators 114 that may include subnetworks 118, 120arranged in any combination of topologies such as token ring, mesh, adhoc, and the like.

In embodiments the wireless energy transfer system may comprise acentralized sensing and control system 108. In embodiments parameters ofthe resonators, energy sources, energy drains, network topologies,operating parameters, etc. may be monitored and adjusted from a controlprocessor to meet specific operating parameters of the system. A centralcontrol processor may adjust parameters of individual components of thesystem to optimize global energy transfer efficiency, to optimize theamount of power transferred, and the like. Other embodiments may bedesigned to have a substantially distributed sensing and control system.Sensing and control may be incorporated into each resonator or group ofresonators, energy sources, energy drains, and the like and may beconfigured to adjust the parameters of the individual components in thegroup to maximize or minimize the power delivered, to maximize energytransfer efficiency in that group and the like.

In embodiments, components of the wireless energy transfer system mayhave wireless or wired data communication links to other components suchas devices, sources, repeaters, power sources, resonators, and the likeand may transmit or receive data that can be used to enable thedistributed or centralized sensing and control. A wireless communicationchannel may be separate from the wireless energy transfer channel, or itmay be the same. In one embodiment the resonators used for powerexchange may also be used to exchange information. In some cases,information may be exchanged by modulating a component in a source ordevice circuit and sensing that change with port parameter or othermonitoring equipment. Resonators may signal each other by tuning,changing, varying, dithering, and the like, the resonator parameterssuch as the impedance of the resonators which may affect the reflectedimpedance of other resonators in the system. The systems and methodsdescribed herein may enable the simultaneous transmission of power andcommunication signals between resonators in wireless power transmissionsystems, or it may enable the transmission of power and communicationsignals during different time periods or at different frequencies usingthe same magnetic fields that are used during the wireless energytransfer. In other embodiments wireless communication may be enabledwith a separate wireless communication channel such as WiFi, Bluetooth,Infrared, NFC, and the like.

In embodiments, a wireless energy transfer system may include multipleresonators and overall system performance may be improved by control ofvarious elements in the system. For example, devices with lower powerrequirements may tune their resonant frequency away from the resonantfrequency of a high-power source that supplies power to devices withhigher power requirements. For another example, devices needing lesspower may adjust their rectifier circuits so that they draw less powerfrom the source. In these ways, low and high power devices may safelyoperate or charge from a single high power source. In addition, multipledevices in a charging zone may find the power available to themregulated according to any of a variety of consumption controlalgorithms such as First-Come-First-Serve, Best Effort, GuaranteedPower, etc. The power consumption algorithms may be hierarchical innature, giving priority to certain users or types of devices, or it maysupport any number of users by equally sharing the power that isavailable in the source. Power may be shared by any of the multiplexingtechniques described in this disclosure.

In embodiments electromagnetic resonators may be realized or implementedusing a combination of shapes, structures, and configurations.Electromagnetic resonators may include an inductive element, adistributed inductance, or a combination of inductances with a totalinductance, L, and a capacitive element, a distributed capacitance, or acombination of capacitances, with a total capacitance, C. A minimalcircuit model of an electromagnetic resonator comprising capacitance,inductance and resistance, is shown in FIG. 2F. The resonator mayinclude an inductive element 238 and a capacitive element 240. Providedwith initial energy, such as electric field energy stored in thecapacitor 240, the system will oscillate as the capacitor dischargestransferring energy into magnetic field energy stored in the inductor238 which in turn transfers energy back into electric field energystored in the capacitor 240. Intrinsic losses in these electromagneticresonators include losses due to resistance in the inductive andcapacitive elements and to radiation losses, and are represented by theresistor, R, 242 in FIG. 2F.

FIG. 2A shows a simplified drawing of an exemplary magnetic resonatorstructure. The magnetic resonator may include a loop of conductor with acentral axis 206 acting as an inductive element 202 and a capacitiveelement 204 at the ends of the conductor loop. The inductor 202 andcapacitor 204 of an electromagnetic resonator may be bulk circuitelements, or the inductance and capacitance may be distributed and mayresult from the way the conductors are formed, shaped, or positioned, inthe structure.

For example, the inductor 202 may be realized by shaping a conductor toenclose a surface area, as shown in FIG. 2A. This type of resonator maybe referred to as a capacitively-loaded loop inductor. Note that we mayuse the terms “loop” or “coil” to indicate generally a conductingstructure (wire, tube, strip, etc.), enclosing a surface of any shapeand dimension, with any number of turns. In FIG. 2A, the enclosedsurface area is circular, but the surface may be any of a wide varietyof other shapes and sizes and may be designed to achieve certain systemperformance specifications. In embodiments the inductance may berealized using inductor elements, distributed inductance, networks,arrays, series and parallel combinations of inductors and inductances,and the like. The inductance may be fixed or variable and may be used tovary impedance matching as well as resonant frequency operatingconditions.

There are a variety of ways to realize the capacitance required toachieve the desired resonant frequency for a resonator structure.Capacitor plates 204 may be formed and utilized as shown in FIG. 2A, orthe capacitance may be distributed and be realized between adjacentwindings of a multi-loop conductor. The capacitance may be realizedusing capacitor elements, distributed capacitance, networks, arrays,series and parallel combinations of capacitances, and the like. Thecapacitance may be fixed or variable and may be used to vary impedancematching as well as resonant frequency operating conditions.

The inductive elements used in magnetic resonators may contain more thanone loop and may spiral inward or outward or up or down or in somecombination of directions. In general, the magnetic resonators may havea variety of shapes, sizes and number of turns and they may be composedof a variety of conducing materials. The conductor 210, for example, maybe a wire, a Litz wire, a ribbon, a pipe, a trace formed from conductingink, paint, gels, and the like or from single or multiple traces printedon a circuit board. An exemplary embodiment of a trace pattern on asubstrate 208 forming inductive loops is depicted in FIG. 2B.

In embodiments the inductive elements may be formed using magneticmaterials of any size, shape thickness, and the like, and of materialswith a wide range of permeability and loss values. These magneticmaterials may be solid blocks, they may enclose hollow volumes, they maybe formed from many smaller pieces of magnetic material tiled and orstacked together, and they may be integrated with conducting sheets orenclosures made from highly conducting materials. Conductors may bewrapped around the magnetic materials to generate the magnetic field.These conductors may be wrapped around one or more than one axis of thestructure. Multiple conductors may be wrapped around the magneticmaterials and combined in parallel, or in series, or via a switch toform customized near-field patterns and/or to orient the dipole momentof the structure. Examples of resonators comprising magnetic materialare depicted in FIGS. 2C, 2D, 2E. In FIG. 2D the resonator comprisesloops of conductor 224 wrapped around a core of magnetic material 222creating a structure that has a magnetic dipole moment 228 that isparallel to the axis of the loops of the conductor 224. The resonatormay comprise multiple loops of conductor 216, 212 wrapped in orthogonaldirections around the magnetic material 214 forming a resonator with amagnetic dipole moment 218, 220 that may be oriented in more than onedirection as depicted in FIG. 2C, depending on how the conductors aredriven. In FIG. 2E the resonator comprises loops of conductor 234wrapped around a core of magnetic material 232 creating a structure thathas a magnetic dipole moment 236 that is parallel to the axis of theloops of the conductor 234.

An electromagnetic resonator may have a characteristic, natural, orresonant frequency determined by its physical properties. This resonantfrequency is the frequency at which the energy stored by the resonatoroscillates between that stored by the electric field, W_(E),(W_(E)=q²/2C, where q is the charge on the capacitor, C) and that storedby the magnetic field, W_(B), (W_(B)=Li²/2, where i is the currentthrough the inductor, L) of the resonator. The frequency at which thisenergy is exchanged may be called the characteristic frequency, thenatural frequency, or the resonant frequency of the resonator, and isgiven by ω,

$\omega = {{2\pi\; f} = \sqrt{\sqrt{\frac{1}{LC}.}}}$The resonant frequency of the resonator may be changed by tuning theinductance, L, and/or the capacitance, C, of the resonator. In oneembodiment system parameters are dynamically adjustable or tunable toachieve as close as possible to optimal operating conditions. However,based on the discussion above, efficient enough energy exchange may berealized even if some system parameters are not variable or componentsare not capable of dynamic adjustment.

In embodiments a resonator may comprise an inductive element coupled tomore than one capacitor arranged in a network of capacitors and circuitelements. In embodiments the coupled network of capacitors and circuitelements may be used to define more than one resonant frequency of theresonator. In embodiments a resonator may be resonant, or partiallyresonant, at more than one frequency.

In embodiments, a wireless power source may comprise of at least oneresonator coil coupled to a power supply, which may be a switchingamplifier, such as a class-D amplifier or a class-E amplifier or acombination thereof. In this case, the resonator coil is effectively apower load to the power supply. In embodiments, a wireless power devicemay comprise of at least one resonator coil coupled to a power load,which may be a switching rectifier, such as a class-D rectifier or aclass-E rectifier or a combination thereof. In this case, the resonatorcoil is effectively a power supply for the power load, and the impedanceof the load directly relates also to the work-drainage rate of the loadfrom the resonator coil. The efficiency of power transmission between apower supply and a power load may be impacted by how closely matched theoutput impedance of the power source is to the input impedance of theload. Power may be delivered to the load at a maximum possibleefficiency, when the input impedance of the load is equal to the complexconjugate of the internal impedance of the power supply. Designing thepower supply or power load impedance to obtain a maximum powertransmission efficiency is often called “impedance matching”, and mayalso referred to as optimizing the ratio of useful-to-lost powers in thesystem. Impedance matching may be performed by adding networks or setsof elements such as capacitors, inductors, transformers, switches,resistors, and the like, to form impedance matching networks between apower supply and a power load. In embodiments, mechanical adjustmentsand changes in element positioning may be used to achieve impedancematching. For varying loads, the impedance matching network may includevariable components that are dynamically adjusted to ensure that theimpedance at the power supply terminals looking towards the load and thecharacteristic impedance of the power supply remain substantiallycomplex conjugates of each other, even in dynamic environments andoperating scenarios.

In embodiments, impedance matching may be accomplished by tuning theduty cycle, and/or the phase, and/or the frequency of the driving signalof the power supply or by tuning a physical component within the powersupply, such as a capacitor. Such a tuning mechanism may be advantageousbecause it may allow impedance matching between a power supply and aload without the use of a tunable impedance matching network, or with asimplified tunable impedance matching network, such as one that hasfewer tunable components for example. In embodiments, tuning the dutycycle, and/or frequency, and/or phase of the driving signal to a powersupply may yield a dynamic impedance matching system with an extendedtuning range or precision, with higher power, voltage and/or currentcapabilities, with faster electronic control, with fewer externalcomponents, and the like.

In some wireless energy transfer systems the parameters of the resonatorsuch as the inductance may be affected by environmental conditions suchas surrounding objects, temperature, orientation, number and position ofother resonators and the like. Changes in operating parameters of theresonators may change certain system parameters, such as the efficiencyof transferred power in the wireless energy transfer. For example,high-conductivity materials located near a resonator may shift theresonant frequency of a resonator and detune it from other resonantobjects. In some embodiments, a resonator feedback mechanism is employedthat corrects its frequency by changing a reactive element (e.g., aninductive element or capacitive element). In order to achieve acceptablematching conditions, at least some of the system parameters may need tobe dynamically adjustable or tunable. All the system parameters may bedynamically adjustable or tunable to achieve approximately the optimaloperating conditions. However, efficient enough energy exchange may berealized even if all or some system parameters are not variable. In someexamples, at least some of the devices may not be dynamically adjusted.In some examples, at least some of the sources may not be dynamicallyadjusted. In some examples, at least some of the intermediate resonatorsmay not be dynamically adjusted. In some examples, none of the systemparameters may be dynamically adjusted.

In some embodiments changes in parameters of components may be mitigatedby selecting components with characteristics that change in acomplimentary or opposite way or direction when subjected to differencesin operating environment or operating point. In embodiments, a systemmay be designed with components, such as capacitors, that have anopposite dependence or parameter fluctuation due to temperature, powerlevels, frequency, and the like. In some embodiments, the componentvalues as a function of temperature may be stored in a look-up table ina system microcontroller and the reading from a temperature sensor maybe used in the system control feedback loop to adjust other parametersto compensate for the temperature induced component value changes.

In some embodiments the changes in parameter values of components may becompensated with active tuning circuits comprising tunable components.Circuits that monitor the operating environment and operating point ofcomponents and system may be integrated in the design. The monitoringcircuits may provide the signals necessary to actively compensate forchanges in parameters of components. For example, a temperature readingmay be used to calculate expected changes in, or to indicate previouslymeasured values of, capacitance of the system allowing compensation byswitching in other capacitors or tuning capacitors to maintain thedesired capacitance over a range of temperatures. In embodiments, the RFamplifier switching waveforms may be adjusted to compensate forcomponent value or load changes in the system. In some embodiments thechanges in parameters of components may be compensated with activecooling, heating, active environment conditioning, and the like.

The parameter measurement circuitry may measure or monitor certainpower, voltage, and current, signals in the system, and processors orcontrol circuits may adjust certain settings or operating parametersbased on those measurements. In addition the magnitude and phase ofvoltage and current signals, and the magnitude of the power signals,throughout the system may be accessed to measure or monitor the systemperformance. The measured signals referred to throughout this disclosuremay be any combination of port parameter signals, as well as voltagesignals, current signals, power signals, temperatures signals and thelike. These parameters may be measured using analog or digitaltechniques, they may be sampled and processed, and they may be digitizedor converted using a number of known analog and digital processingtechniques. In embodiments, preset values of certain measured quantitiesare loaded in a system controller or memory location and used in variousfeedback and control loops. In embodiments, any combination of measured,monitored, and/or preset signals may be used in feedback circuits orsystems to control the operation of the resonators and/or the system.

Adjustment algorithms may be used to adjust the frequency, Q, and/orimpedance of the magnetic resonators. The algorithms may take as inputsreference signals related to the degree of deviation from a desiredoperating point for the system and may output correction or controlsignals related to that deviation that control variable or tunableelements of the system to bring the system back towards the desiredoperating point or points. The reference signals for the magneticresonators may be acquired while the resonators are exchanging power ina wireless power transmission system, or they may be switched out of thecircuit during system operation. Corrections to the system may beapplied or performed continuously, periodically, upon a thresholdcrossing, digitally, using analog methods, and the like.

In embodiments, lossy extraneous materials and objects may introducepotential reductions in efficiencies by absorbing the magnetic and/orelectric energy of the resonators of the wireless power transmissionsystem. Those impacts may be mitigated in various embodiments bypositioning resonators to minimize the effects of the lossy extraneousmaterials and objects and by placing structural field shaping elements(e.g., conductive structures, plates and sheets, magnetic materialstructures, plates and sheets, and combinations thereof) to minimizetheir effect.

One way to reduce the impact of lossy materials on a resonator is to usehigh-conductivity materials, magnetic materials, or combinations thereofto shape the resonator fields such that they avoid the lossy objects. Inan exemplary embodiment, a layered structure of high-conductivitymaterial and magnetic material may tailor, shape, direct, reorient, etc.the resonator's electromagnetic fields so that they avoid lossy objectsin their vicinity by deflecting the fields. FIG. 2D shows a top view ofa resonator with a sheet of conductor 226 below the magnetic materialthat may be used to tailor the fields of the resonator so that theyavoid lossy objects that may be below the sheet of conductor 226. Thelayer or sheet of good conductor 226 may comprise any high conductivitymaterials such as copper, silver, aluminum, as may be most appropriatefor a given application. In certain embodiments, the layer or sheet ofgood conductor is thicker than the skin depth of the conductor at theresonator operating frequency. The conductor sheet may be preferablylarger than the size of the resonator, extending beyond the physicalextent of the resonator. FIG. 2E shows a top view of a resonator with asegmented sheet of conductor 230.

In environments and systems where the amount of power being transmittedcould present a safety hazard to a person or animal that may intrudeinto the active field volume, safety measures may be included in thesystem. In embodiments where power levels require particularized safetymeasures, the packaging, structure, materials, and the like of theresonators may be designed to provide a spacing or “keep away” zone fromthe conducting loops in the magnetic resonator. To provide furtherprotection, high-Q resonators and power and control circuitry may belocated in enclosures that confine high voltages or currents to withinthe enclosure, that protect the resonators and electrical componentsfrom weather, moisture, sand, dust, and other external elements, as wellas from impacts, vibrations, scrapes, explosions, and other types ofmechanical shock. Such enclosures call for attention to various factorssuch as thermal dissipation to maintain an acceptable operatingtemperature range for the electrical components and the resonator. Inembodiments, enclosure may be constructed of non-lossy materials such ascomposites, plastics, wood, concrete, and the like and may be used toprovide a minimum distance from lossy objects to the resonatorcomponents. A minimum separation distance from lossy objects orenvironments which may include metal objects, salt water, oil and thelike, may improve the efficiency of wireless energy transfer. Inembodiments, a “keep away” zone may be used to increase the perturbed Qof a resonator or system of resonators. In embodiments a minimumseparation distance may provide for a more reliable or more constantoperating parameters of the resonators.

In embodiments, resonators and their respective sensor and controlcircuitry may have various levels of integration with other electronicand control systems and subsystems. In some embodiments the power andcontrol circuitry and the device resonators are completely separatemodules or enclosures with minimal integration to existing systems,providing a power output and a control and diagnostics interface. Insome embodiments a device is configured to house a resonator and circuitassembly in a cavity inside the enclosure, or integrated into thehousing or enclosure of the device.

Example Resonator Circuitry

FIGS. 3 and 4 show high level block diagrams depicting power generation,monitoring, and control components for exemplary sources of a wirelessenergy transfer system. FIG. 3 is a block diagram of a source comprisinga half-bridge switching power amplifier and some of the associatedmeasurement, tuning, and control circuitry. FIG. 4 is a block diagram ofa source comprising a full-bridge switching amplifier and some of theassociated measurement, tuning, and control circuitry.

The half bridge system topology depicted in FIG. 3 may comprise aprocessing unit that executes a control algorithm 328. The processingunit executing a control algorithm 328 may be a microcontroller, anapplication specific circuit, a field programmable gate array, aprocessor, a digital signal processor, and the like. The processing unitmay be a single device or it may be a network of devices. The controlalgorithm may run on any portion of the processing unit. The algorithmmay be customized for certain applications and may comprise acombination of analog and digital circuits and signals. The masteralgorithm may measure and adjust voltage signals and levels, currentsignals and levels, signal phases, digital count settings, and the like.

The system may comprise an optional source/device and/or source/otherresonator communication controller 332 coupled to wireless communicationcircuitry 312. The optional source/device and/or source/other resonatorcommunication controller 332 may be part of the same processing unitthat executes the master control algorithm, it may a part or a circuitwithin a microcontroller 302, it may be external to the wireless powertransmission modules, it may be substantially similar to communicationcontrollers used in wire powered or battery powered applications butadapted to include some new or different functionality to enhance orsupport wireless power transmission.

The system may comprise a PWM generator 306 coupled to at least twotransistor gate drivers 334 and may be controlled by the controlalgorithm. The two transistor gate drivers 334 may be coupled directlyor via gate drive transformers to two power transistors 336 that drivethe source resonator coil 344 through impedance matching networkcomponents 342. The power transistors 336 may be coupled and poweredwith an adjustable DC supply 304 and the adjustable DC supply 304 may becontrolled by a variable bus voltage, Vbus. The Vbus controller may becontrolled by the control algorithm 328 and may be part of, orintegrated into, a microcontroller 302 or other integrated circuits. TheVbus controller 326 may control the voltage output of an adjustable DCsupply 304 which may be used to control power output of the amplifierand power delivered to the resonator coil 344.

The system may comprise sensing and measurement circuitry includingsignal filtering and buffering circuits 318, 320 that may shape, modify,filter, process, buffer, and the like, signals prior to their input toprocessors and/or converters such as analog to digital converters (ADC)314, 316, for example. The processors and converters such as ADCs 314,316 may be integrated into a microcontroller 302 or may be separatecircuits that may be coupled to a processing core 330. Based on measuredsignals, the control algorithm 328 may generate, limit, initiate,extinguish, control, adjust, or modify the operation of any of the PWMgenerator 306, the communication controller 332, the Vbus control 326,the source impedance matching controller 338, the filter/bufferingelements, 318, 320, the converters, 314, 316, the resonator coil 344,and may be part of, or integrated into, a microcontroller 302 or aseparate circuit. The impedance matching networks 342 and resonatorcoils 344 may include electrically controllable, variable, or tunablecomponents such as capacitors, switches, inductors, and the like, asdescribed herein, and these components may have their component valuesor operating points adjusted according to signals received from thesource impedance matching controller 338. Components may be tuned toadjust the operation and characteristics of the resonator including thepower delivered to and by the resonator, the resonant frequency of theresonator, the impedance of the resonator, the Q of the resonator, andany other coupled systems, and the like. The resonator may be any typeor structure resonator described herein including a capacitively loadedloop resonator, a planer resonator comprising a magnetic material or anycombination thereof.

The full bridge system topology depicted in FIG. 4 may comprise aprocessing unit that executes a master control algorithm 328. Theprocessing unit executing the control algorithm 328 may be amicrocontroller, an application specific circuit, a field programmablegate array, a processor, a digital signal processor, and the like. Thesystem may comprise a source/device and/or source/other resonatorcommunication controller 332 coupled to wireless communication circuitry312. The source/device and/or source/other resonator communicationcontroller 332 may be part of the same processing unit that executesthat master control algorithm, it may a part or a circuit within amicrocontroller 302, it may be external to the wireless powertransmission modules, it may be substantially similar to communicationcontrollers used in wire powered or battery powered applications butadapted to include some new or different functionality to enhance orsupport wireless power transmission.

The system may comprise a PWM generator 410 with at least two outputscoupled to at least four transistor gate drivers 334 that may becontrolled by signals generated in a master control algorithm. The fourtransistor gate drivers 334 may be coupled to four power transistors 336directly or via gate drive transformers that may drive the sourceresonator coil 344 through impedance matching networks 342. The powertransistors 336 may be coupled and powered with an adjustable DC supply304 and the adjustable DC supply 304 may be controlled by a Vbuscontroller 326 which may be controlled by a master control algorithm.The Vbus controller 326 may control the voltage output of the adjustableDC supply 304 which may be used to control power output of the amplifierand power delivered to the resonator coil 344.

The system may comprise sensing and measurement circuitry includingsignal filtering and buffering circuits 318, 320 and differential/singleended conversion circuitry 402, 404 that may shape, modify, filter,process, buffer, and the like, signals prior to being input toprocessors and/or converters such as analog to digital converters (ADC)314, 316. The processors and/or converters such as ADC 314, 316 may beintegrated into a microcontroller 302 or may be separate circuits thatmay be coupled to a processing core 330. Based on measured signals, themaster control algorithm may generate, limit, initiate, extinguish,control, adjust, or modify the operation of any of the PWM generator410, the communication controller 332, the Vbus controller 326, thesource impedance matching controller 338, the filter/buffering elements,318, 320, differential/single ended conversion circuitry 402, 404, theconverters, 314, 316, the resonator coil 344, and may be part of orintegrated into a microcontroller 302 or a separate circuit.

Impedance matching networks 342 and resonator coils 344 may compriseelectrically controllable, variable, or tunable components such ascapacitors, switches, inductors, and the like, as described herein, andthese components may have their component values or operating pointsadjusted according to signals received from the source impedancematching controller 338. Components may be tuned to enable tuning of theoperation and characteristics of the resonator including the powerdelivered to and by the resonator, the resonant frequency of theresonator, the impedance of the resonator, the Q of the resonator, andany other coupled systems, and the like. The resonator may be any typeor structure resonator described herein including a capacitively loadedloop resonator, a planar resonator comprising a magnetic material or anycombination thereof.

Impedance matching networks may comprise fixed value components such ascapacitors, inductors, and networks of components as described herein.Parts of the impedance matching networks, A, B and C, may compriseinductors, capacitors, transformers, and series and parallelcombinations of such components, as described herein. In someembodiments, parts of the impedance matching networks A, B, and C, maybe empty (short-circuited). In some embodiments, part B comprises aseries combination of an inductor and a capacitor, and part C is empty.

The full bridge topology may allow operation at higher output powerlevels using the same DC bus voltage as an equivalent half bridgeamplifier. The half bridge exemplary topology of FIG. 3 may provide asingle-ended drive signal, while the exemplary full bridge topology ofFIG. 4 may provide a differential drive to the source resonator 308. Theimpedance matching topologies and components and the resonator structuremay be different for the two systems, as discussed herein.

The exemplary systems depicted in FIGS. 3 and 4 may further includefault detection circuitry 340 that may be used to trigger the shutdownof the microcontroller in the source amplifier or to change or interruptthe operation of the amplifier. This protection circuitry may comprise ahigh speed comparator or comparators to monitor the amplifier returncurrent, the amplifier bus voltage (Vbus) from the DC supply 304, thevoltage across the source resonator 308 and/or the optional tuningboard, or any other voltage or current signals that may cause damage tocomponents in the system or may yield undesirable operating conditions.Preferred embodiments may depend on the potentially undesirableoperating modes associated with different applications. In someembodiments, protection circuitry may not be implemented or circuits maynot be populated. In some embodiments, system and component protectionmay be implemented as part of a master control algorithm and othersystem monitoring and control circuits. In embodiments, dedicated faultcircuitry 340 may include an output (not shown) coupled to a mastercontrol algorithm 328 that may trigger a system shutdown, a reduction ofthe output power (e.g. reduction of Vbus), a change to the PWMgenerator, a change in the operating frequency, a change to a tuningelement, or any other reasonable action that may be implemented by thecontrol algorithm 328 to adjust the operating point mode, improve systemperformance, and/or provide protection.

As described herein, sources in wireless power transfer systems may usea measurement of the input impedance of the impedance matching network342 driving source resonator coil 344 as an error or control signal fora system control loop that may be part of the master control algorithm.In exemplary embodiments, variations in any combination of threeparameters may be used to tune the wireless power source to compensatefor changes in environmental conditions, for changes in coupling, forchanges in device power demand, for changes in module, circuit,component or subsystem performance, for an increase or decrease in thenumber or sources, devices, or repeaters in the system, for userinitiated changes, and the like. In exemplary embodiments, changes tothe amplifier duty cycle, to the component values of the variableelectrical components such as variable capacitors and inductors, and tothe DC bus voltage may be used to change the operating point oroperating range of the wireless source and improve some system operatingvalue. The specifics of the control algorithms employed for differentapplications may vary depending on the desired system performance andbehavior.

Impedance measurement circuitry such as described herein, and shown inFIGS. 3 and 4, may be implemented using two-channel simultaneoussampling ADCs and these ADCs may be integrated into a microcontrollerchip or may be part of a separate circuit. Simultaneously sampling ofthe voltage and current signals at the input to a source resonator'simpedance matching network and/or the source resonator may yield thephase and magnitude information of the current and voltage signals andmay be processed using known signal processing techniques to yieldcomplex impedance parameters. In some embodiments, monitoring only thevoltage signals or only the current signals may be sufficient.

The impedance measurements described herein may use direct samplingmethods which may be relatively simpler than some other known samplingmethods. In embodiments, measured voltage and current signals may beconditioned, filtered and scaled by filtering/buffering circuitry beforebeing input to ADCs. In embodiments, the filter/buffering circuitry maybe adjustable to work at a variety of signal levels and frequencies, andcircuit parameters such as filter shapes and widths may be adjustedmanually, electronically, automatically, in response to a controlsignal, by the master control algorithm, and the like. Exemplaryembodiments of filter/buffering circuits are shown in FIGS. 3, 4, and 5.

FIG. 5 shows more detailed views of exemplary circuit components thatmay be used in filter/buffering circuitry. In embodiments, and dependingon the types of ADCs used in the system designs, single-ended amplifiertopologies may reduce the complexity of the analog signal measurementpaths used to characterize system, subsystem, module, and/or componentperformance by eliminating the need for hardware 508 to convert fromdifferential to single-ended signal formats. In other implementations,differential signal formats may be preferable. The implementations shownin FIG. 5 are exemplary, and should not be construed to be the onlypossible way to implement the functionality described herein. Rather itshould be understood that the analog signal path may employ componentswith different input requirements and hence may have different signalpath architectures.

In both the single ended and differential amplifier topologies, theinput current to the impedance matching networks 342 driving theresonator coils 344 may be obtained by measuring the voltage across acapacitor 324, or via a current sensor of some type. For the exemplarysingle-ended amplifier topology in FIG. 3, the current may be sensed onthe ground return path from the impedance matching network 342. For theexemplary differential power amplifier depicted in FIG. 4, the inputcurrent to the impedance matching networks 342 driving the resonatorcoils 344 may be measured using a differential amplifier across theterminals of a capacitor 324 or via a current sensor of some type. Inthe differential topology of FIG. 4, the capacitor 324 may be duplicatedat the negative output terminal of the source power amplifier.

In both topologies, after single ended signals representing the inputvoltage and current to the source resonator and impedance matchingnetwork are obtained, the signals may be filtered 502 to obtain thedesired portions of the signal waveforms. In embodiments, the signalsmay be filtered to obtain the fundamental component of the signals. Inembodiments, the type of filtering performed, such as low pass,bandpass, notch, and the like, as well as the filter topology used, suchas elliptical, Chebyshev, Butterworth, and the like, may depend on thespecific requirements of the system. In some embodiments, no filteringwill be required.

The voltage and current signals may be amplified by an optionalamplifier 504. The gain of the optional amplifier 504 may be fixed orvariable. The gain of the amplifier may be controlled manually,electronically, automatically, in response to a control signal, and thelike. The gain of the amplifier may be adjusted in a feedback loop, inresponse to a control algorithm, by the master control algorithm, andthe like. In embodiments, required performance specifications for theamplifier may depend on signal strength and desired measurementaccuracy, and may be different for different application scenarios andcontrol algorithms.

The measured analog signals may have a DC offset added to them, 506,which may be required to bring the signals into the input voltage rangeof the ADC which for some systems may be 0 to 3.3V. In some systems thisstage may not be required, depending on the specifications of theparticular ADC used.

As described above, the efficiency of power transmission between a powergenerator and a power load may be impacted by how closely matched theoutput impedance of the generator is to the input impedance of the load.In an exemplary system as shown in FIG. 6A, power may be delivered tothe load at a maximum possible efficiency, when the input impedance ofthe load 604 is equal to the complex conjugate of the internal impedanceof the power generator or the power amplifier 602. Designing thegenerator or load impedance to obtain a high and/or maximum powertransmission efficiency may be called “impedance matching”. Impedancematching may be performed by inserting appropriate networks or sets ofelements such as capacitors, resistors, inductors, transformers,switches and the like, to form an impedance matching network 606,between a power generator 602 and a power load 604 as shown in FIG. 6B.In other embodiments, mechanical adjustments and changes in elementpositioning may be used to achieve impedance matching. As describedabove for varying loads, the impedance matching network 606 may includevariable components that are dynamically adjusted to ensure that theimpedance at the generator terminals looking towards the load and thecharacteristic impedance of the generator remain substantially complexconjugates of each other, even in dynamic environments and operatingscenarios. In embodiments, dynamic impedance matching may beaccomplished by tuning the duty cycle, and/or the phase, and/or thefrequency of the driving signal of the power generator or by tuning aphysical component within the power generator, such as a capacitor, asdepicted in FIG. 6C. Such a tuning mechanism may be advantageous becauseit may allow impedance matching between a power generator 608 and a loadwithout the use of a tunable impedance matching network, or with asimplified tunable impedance matching network 606, such as one that hasfewer tunable components for example. In embodiments, tuning the dutycycle, and/or frequency, and/or phase of the driving signal to a powergenerator may yield a dynamic impedance matching system with an extendedtuning range or precision, with higher power, voltage and/or currentcapabilities, with faster electronic control, with fewer externalcomponents, and the like. The impedance matching methods, architectures,algorithms, protocols, circuits, measurements, controls, and the like,described below, may be useful in systems where power generators drivehigh-Q magnetic resonators and in high-Q wireless power transmissionsystems as described herein. In wireless power transfer systems a powergenerator may be a power amplifier driving a resonator, sometimesreferred to as a source resonator, which may be a load to the poweramplifier. In wireless power applications, it may be preferable tocontrol the impedance matching between a power amplifier and a resonatorload to control the efficiency of the power delivery from the poweramplifier to the resonator. The impedance matching may be accomplished,or accomplished in part, by tuning or adjusting the duty cycle, and/orthe phase, and/or the frequency of the driving signal of the poweramplifier that drives the resonator.

Wireless Power Repeater Resonators

A wireless power transfer system may incorporate a repeater resonatorconfigured to exchange energy with one or more source resonators, deviceresonators, or additional repeater resonators. A repeater resonator maybe used to extend the range of wireless power transfer. A repeaterresonator may be used to change, distribute, concentrate, enhance, andthe like, the magnetic field generated by a source. A repeater resonatormay be used to guide magnetic fields of a source resonator around lossyand/or metallic objects that might otherwise block the magnetic field. Arepeater resonator may be used to eliminate or reduce areas of low powertransfer, or areas of low magnetic field around a source. A repeaterresonator may be used to improve the coupling efficiency between asource and a target device resonator or resonators, and may be used toimprove the coupling between resonators with different orientations, orwhose dipole moments are not favorably aligned.

An oscillating magnetic field produced by a source magnetic resonatorcan cause electrical currents in the conductor part of the repeaterresonator. These electrical currents may create their own magnetic fieldas they oscillate in the resonator thereby extending or changing themagnetic field area or the magnetic field distribution of the source.

In embodiments, a repeater resonator may operate as a source for one ormore device resonators. In other embodiments, a device resonator maysimultaneously receive a magnetic field and repeat a magnetic field. Instill other embodiments, a resonator may alternate between operating asa source resonator, device resonator or repeater resonator. Thealternation may be achieved through time multiplexing, frequencymultiplexing, self-tuning, or through a centralized control algorithm.In embodiments, multiple repeater resonators may be positioned in anarea and tuned in and out of resonance to achieve a spatially varyingmagnetic field. In embodiments, a local area of strong magnetic fieldmay be created by an array of resonators, and the positioned of thestrong field area may be moved around by changing electrical componentsor operating characteristics of the resonators in the array.

In embodiments a repeater resonator may be a capacitively loaded loopmagnetic resonator. In embodiments a repeater resonator may be acapacitively loaded loop magnetic resonator wrapper around magneticmaterial. In embodiments the repeater resonator may be tuned to have aresonant frequency that is substantially equal to that of the frequencyof a source or device or at least one other repeater resonator withwhich the repeater resonator is designed to interact or couple. In otherembodiments the repeater resonator may be detuned to have a resonantfrequency that is substantially greater than, or substantially less thanthe frequency of a source or device or at least one other repeaterresonator with which the repeater resonator is designed to interact orcouple. Preferably, the repeater resonator may be a high-Q magneticresonator with an intrinsic quality factor, Q_(r), of 100 or more. Insome embodiments the repeater resonator may have quality factor of lessthan 100. In some embodiments,

$\sqrt{\sqrt{Q_{s}Q_{r}}} > 100.$In other embodiments,

$\sqrt{\sqrt{Q_{d}Q_{r}}} > 100.$In still other embodiments,

$\sqrt{\sqrt{Q_{r\; 1}Q_{r\; 2}}} > 100.$

In embodiments, the repeater resonator may include only the inductiveand capacitive components that comprise the resonator without anyadditional circuitry, for connecting to sources, loads, controllers,monitors, control circuitry and the like. In some embodiments therepeater resonator may include additional control circuitry, tuningcircuitry, measurement circuitry, or monitoring circuitry. Additionalcircuitry may be used to monitor the voltages, currents, phase,inductance, capacitance, and the like of the repeater resonator. Themeasured parameters of the repeater resonator may be used to adjust ortune the repeater resonator. A controller or a microcontroller may beused by the repeater resonator to actively adjust the capacitance,resonant frequency, inductance, resistance, and the like of the repeaterresonator. A tunable repeater resonator may be necessary to prevent therepeater resonator from exceeding its voltage, current, temperature, orpower limits. A repeater resonator may for example detune its resonantfrequency to reduce the amount of power transferred to the repeaterresonator, or to modulate or control how much power is transferred toother devices or resonators that couple to the repeater resonator.

In some embodiments the power and control circuitry of the repeaterresonators may be powered by the energy captured by the repeaterresonator. The repeater resonator may include AC to DC, AC to AC, or DCto DC converters and regulators to provide power to the control ormonitoring circuitry. In some embodiments the repeater resonator mayinclude an additional energy storage component such as a battery or asuper capacitor to supply power to the power and control circuitryduring momentary or extended periods of wireless power transferinterruptions. The battery, super capacitor, or other power storagecomponent may be periodically or continuously recharged during normaloperation when the repeater resonator is within range of any wirelesspower source.

In some embodiments the repeater resonator may include communication orsignaling capability such as WiFi, Bluetooth, near field, and the likethat may be used to coordinate power transfer from a source or multiplesources to a specific location or device or to multiple locations ordevices. Repeater resonators spread across a location may be signaled toselectively tune or detune from a specific resonant frequency to extendthe magnetic field from a source to a specific location, area, ordevice. Multiple repeater resonators may be used to selectively tune, ordetune, or relay power from a source to specific areas or devices.

The repeater resonators may include a device into which some, most, orall of the energy transferred or captured from the source to therepeater resonator may be available for use. The repeater resonator mayprovide power to one or more electric or electronic devices whilerelaying or extending the range of the source. In some embodiments lowpower consumption devices such as lights, LEDs, displays, sensors, andthe like may be part of the repeater resonator.

Several possible usage configurations are shown in FIGS. 7-9 showingexample arrangements of a wireless power transfer system that includes asource resonator 704 coupled to a power source 700, a device resonator708 coupled to a device 702, and a repeater resonator 706. In someembodiments, a repeater resonator may be used between the source and thedevice resonator to extend the range of the source. In some embodimentsthe repeater resonator may be positioned after, and further away fromthe source than the device resonator as shown in FIG. 7B. For theconfiguration shown in FIG. 7B more efficient power transfer between thesource and the device may be possible compared to if no repeaterresonator was used. In embodiments of the configuration shown in FIG. 7Bit may be preferable for the repeater resonator to be larger than thedevice resonator.

In some embodiments a repeater resonator may be used to improve couplingbetween non-coaxial resonators or resonators whose dipole moments arenot aligned for high coupling factors or energy transfer efficiencies.For example, a repeater resonator may be used to enhance couplingbetween a source and a device resonator that are not coaxially alignedby placing the repeater resonator between the source and device aligningit with the device resonator as shown in FIG. 8A or aligning with thesource resonator as shown in FIG. 8B.

In some embodiments multiple repeater resonators may be used to extendthe wireless power transfer into multiple directions or multiplerepeater resonators may one after another to extend the power transferdistance as shown in FIG. 9A. In some embodiments, a device resonatorthat is connected to load or electronic device may operatesimultaneously or alternately as a repeater resonator for anotherdevice, repeater resonator, or device resonator as shown in FIG. 9B.Note that there is no theoretical limit to the number of resonators thatmay be used in a given system or operating scenario, but there may bepractical issues that make a certain number of resonators a preferredembodiment. For example, system cost considerations may constrain thenumber of resonators that may be used in a certain application. Systemsize or integration considerations may constrain the size of resonatorsused in certain applications.

In some embodiments the repeater resonator may have dimensions, size, orconfiguration that is the same as the source or device resonators. Insome embodiments the repeater resonator may have dimensions, size, orconfiguration that is different than the source or device resonators.The repeater resonator may have a characteristic size that is largerthan the device resonator or larger than the source resonator, or largerthan both. A larger repeater resonator may improve the coupling betweenthe source and the repeater resonator at a larger separation distancebetween the source and the device.

In some embodiments two or more repeater resonators may be used in awireless power transfer system. In some embodiments two or more repeaterresonators with two or more sources or devices may be used.

Repeater Resonator Modes of Operation

A repeater resonator may be used to enhance or improve wireless powertransfer from a source to one or more resonators built into electronicsthat may be powered or charged on top of, next to, or inside of tables,desks, shelves, cabinets, beds, television stands, and other furniture,structures, and/or containers. A repeater resonator may be used togenerate an energized surface, volume, or area on or next to furniture,structures, and/or containers, without requiring any wired electricalconnections to a power source. A repeater resonator may be used toimprove the coupling and wireless power transfer between a source thatmay be outside of the furniture, structures, and/or containers, and oneor more devices in the vicinity of the furniture, structures, and/orcontainers.

In one exemplary embodiment 1008 depicted in FIG. 10, a repeaterresonator 1004 may be used with a table surface 1002 to energize the topof the table 1018 for powering or recharging of electronic devices 1010,1016, 1014 that have integrated or attached device resonators 1012. Therepeater resonator 1004 may be used to improve the wireless powertransfer from the source 1006 to the device resonators 1012.

In some embodiments the power source and source resonator may be builtinto walls, floors, dividers, ceilings, partitions, wall coverings,floor coverings, and the like. A piece of furniture comprising arepeater resonator may be energized by positioning the furniture and therepeater resonator close to the wall, floor, ceiling, partition, wallcovering, floor covering, and the like that includes the power sourceand source resonator. When close to the source resonator, and configuredto have substantially the same resonant frequency as the sourceresonator, the repeater resonator may couple to the source resonator viaoscillating magnetic fields generated by the source. The oscillatingmagnetic fields produce oscillating currents in the conductor loops ofthe repeater resonator generating an oscillating magnetic field, therebyextending, expanding, reorienting, concentrating, or changing the rangeor direction of the magnetic field generated by the power source andsource resonator alone. The furniture including the repeater resonatormay be effectively “plugged in” or energized and capable of providingwireless power to devices on top, below, or next to the furniture byplacing the furniture next to the wall, floor, ceiling, etc. housing thepower source and source resonator without requiring any physical wiresor wired electrical connections between the furniture and the powersource and source resonator. Wireless power from the repeater resonatormay be supplied to device resonators and electronic devices in thevicinity of the repeater resonator. Power sources may include, but arenot limited to, electrical outlets, the electric grid, generators, solarpanels, fuel cells, wind turbines, batteries, super-capacitors and thelike.

In embodiments, a repeater resonator may enhance the coupling and theefficiency of wireless power transfer to device resonators of smallcharacteristic size, non-optimal orientation, and/or large separationfrom a source resonator. As described above in this document, theefficiency of wireless power transfer may be inversely proportional tothe separation distance between a source and device resonator, and maybe described relative to the characteristic size of the smaller of thesource or device resonators. For example, a device resonator designed tobe integrated into a mobile device such as a smart phone 1012, with acharacteristic size of approximately 5 cm, may be much smaller than asource resonator 1006, designed to be mounted on a wall, with acharacteristic size of 50 cm, and the separation between these tworesonators may be 60 cm or more, or approximately twelve or morecharacteristic sizes of the device resonator, resulting in low powertransfer efficiency. However, if a 50 cm×100 cm repeater resonator isintegrated into a table, as shown in FIG. 10, the separation between thesource and the repeater may be approximately one characteristic size ofthe source resonator, so that the efficiency of power transfer from thesource to the repeater may be high. Likewise, the smart phone deviceresonator placed on top of the table or the repeater resonator, may havea separation distance of less than one characteristic size of the deviceresonator resulting in high efficiency of power transfer between therepeater resonator and the device resonator. While the total transferefficiency between the source and device must take into account both ofthese coupling mechanisms, from the source to the repeater and from therepeater to the device, the use of a repeater resonator may provide forimproved overall efficiency between the source and device resonators.

In embodiments, the repeater resonator may enhance the coupling and theefficiency of wireless power transfer between a source and a device ifthe dipole moments of the source and device resonators are not alignedor are positioned in non-favorable or non-optimal orientations. In theexemplary system configuration depicted in FIG. 10, a capacitivelyloaded loop source resonator integrated into the wall may have a dipolemoment that is normal to the plane of the wall. Flat devices, such asmobile handsets, computers, and the like, that normally rest on a flatsurface may comprise device resonators with dipole moments that arenormal to the plane of the table, such as when the capacitively loadedloop resonators are integrated into one or more of the larger faces ofthe devices such as the back of a mobile handset or the bottom of alaptop. Such relative orientations may yield coupling and the powertransfer efficiencies that are lower than if the dipole moments of thesource and device resonators were in the same plane, for example. Arepeater resonator that has its dipole moment aligned with that of thedipole moment of the device resonators, as shown in FIG. 10, mayincrease the overall efficiency of wireless power transfer between thesource and device because the large size of the repeater resonator mayprovide for strong coupling between the source resonator even though thedipole moments of the two resonators are orthogonal, while theorientation of the repeater resonator is favorable for coupling to thedevice resonator.

In the exemplary embodiment shown in FIG. 10, the direct power transferefficiency between a 50 cm×50 cm source resonator 1006 mounted on thewall and a smart-phone sized device resonator 1012 lying on top of thetable, and approximately 60 cm away from the center of the sourceresonator, with no repeater resonator present, was calculated to beapproximately 19%. Adding a 50 cm×100 cm repeater resonator as shown,and maintaining the relative position and orientation of the source anddevice resonators improved the coupling efficiency from the sourceresonator to the device resonator to approximately 60%. In this oneexample, the coupling efficiency from the source resonator to therepeater resonator was approximately 85% and the coupling efficiencyfrom the repeater resonator to the device resonator was approximately70%. Note that in this exemplary embodiment, the improvement is due bothto the size and the orientation of the repeater resonator.

In embodiments of systems that use a repeater resonator such as theexemplary system depicted in FIG. 10, the repeater resonator may beintegrated into the top surface of the table or furniture. In otherembodiments the repeater resonator may be attached or configured toattach below the table surface. In other embodiments, the repeaterresonator may be integrated in the table legs, panels, or structuralsupports. Repeater resonators may be integrated in table shelves,drawers, leaves, supports, and the like. In yet other embodiments therepeater resonator may be integrated into a mat, pad, cloth, potholder,and the like, that can be placed on top of a table surface. Repeaterresonators may be integrated into items such as bowls, lamps, dishes,picture frames, books, tchotchkes, candle sticks, hot plates, flowerarrangements, baskets, and the like.

In embodiments the repeater resonator may use a core of magneticmaterial or use a form of magnetic material and may use conductingsurfaces to shape the field of the repeater resonator to improvecoupling between the device and source resonators or to shield therepeater resonators from lossy objects that may be part of thefurniture, structures, or containers.

In embodiments, in addition to the exemplary table described above,repeater resonators may be built into chairs, couches, bookshelves,carts, lamps, rugs, carpets, mats, throws, picture frames, desks,counters, closets, doors, windows, stands, islands, cabinets, hutches,fans, shades, shutters, curtains, footstools, and the like.

In embodiments, the repeater resonator may have power and controlcircuitry that may tune the resonator or may control and monitor anynumber of voltages, currents, phases, temperature, fields, and the likewithin the resonator and outside the resonator. The repeater resonatorand the power and control circuitry may be configured to provide one ormore modes of operation. The mode of operation of the repeater resonatormay be configured to act only as repeater resonator. In otherembodiments the mode of operation of the repeater resonator may beconfigured to act as a repeater resonator and/or as a source resonator.The repeater resonator may have an optional power cable or connectorallowing connection to a power source such as an electrical outletproviding an energy source for the amplifiers of the power and controlcircuits for driving the repeater resonator turning it into a source if,for example, a source resonator is not functioning or is not in thevicinity of the furniture. In other embodiments the repeater resonatormay have a third mode of operation in which it may also act as a deviceresonator providing a connection or a plug for connecting electrical orelectronic devices to receive DC or AC power captured by the repeaterresonator. In embodiments these modes be selected by the user or may beautomatically selected by the power and control circuitry of therepeater resonator based on the availability of a source magnetic field,electrical power connection, or a device connection.

In embodiments the repeater resonator may be designed to operate withany number of source resonators that are integrated into walls, floors,other objects or structures. The repeater resonators may be configuredto operate with sources that are retrofitted, hung, or suspendedpermanently or temporarily from walls, furniture, ceilings and the like.

Although the use of a repeater resonator with furniture has beendescribed with the an exemplary embodiment depicting a table and tabletop devices it should be clear to those skilled in the art that the sameconfigurations and designs may be used and deployed in a number ofsimilar configurations, furniture articles, and devices. For example, arepeater resonator may be integrated into a television or a media standor a cabinet such that when the cabinet or stand is placed close to asource the repeater resonator is able to transfer enough energy to poweror recharge electronic devices on the stand or cabinet such as atelevision, movie players, remote controls, speakers, and the like.

In embodiments the repeater resonator may be integrated into a bucket orchest that can be used to store electronics, electronic toys, remotecontrols, game controllers, and the like. When the chest or bucket ispositioned close to a source the repeater resonator may enhance powertransfer from the source to the devices inside the chest or bucket withbuilt in device resonators to allow recharging of the batteries.

Another exemplary embodiment showing the use of a repeater resonator isdepicted in FIG. 11. In this embodiment the repeater resonator may beused in three different modes of operation depending on the usage andstate of the power sources and consumers in the arrangement. The figureshows a handbag 1102 that is depicted as transparent to show internalcomponents. In this exemplary embodiment, there may be a separate bag,satchel, pocket, or compartment 1106 inside the bag 1102 that may beused for storage or carrying of electronic devices 1110 such ascell-phones, MP3 players, cameras, computers, e-readers, iPads, tablets,netbooks, and the like. The compartment may be fitted with a resonator1108 that may be operated in at least three modes of operation. In onemode, the resonator 1108 may be coupled to power and control circuitrythat may include rechargeable or replaceable batteries or battery packsor other types of portable power supplies 1104 and may operate as awireless power source for wirelessly recharging or powering theelectronic devices located in the handbag 1102 or the handbagcompartment 1106. In this configuration and setting, the bag and thecompartment may be used as a portable, wireless recharging or powerstation for electronics.

The resonator 1108 may also be used as a repeater resonator extendingthe wireless power transfer from an external source to improve couplingand wireless power transfer efficiency between the external source andsource resonator (not shown) and the device resonators 1112 of thedevice 1110 inside the bag or the compartment. The repeater resonatormay be larger than the device resonators inside the bag or thecompartment and may have improved coupling to the source.

In another mode, the resonator may be used as a repeater resonator thatboth supplies power to electronic devices and to a portable power supplyused in a wireless power source. When positioned close to an externalsource or source resonator the captured wireless energy may be used by arepeater resonator to charge the battery 1104 or to recharge theportable energy source of the compartment 1106 allowing its future useas a source resonator. The whole bag with the devices may be placed neara source resonator allowing both recharging of the compartment battery1104 and the batteries of the devices 1110 inside the compartment 1106or the bag 1102.

In embodiments the compartment may be built into a bag or container ormay be an additional or independent compartment that may be placed intoany bag or storage enclosure such as a backpack, purse, shopping bag,luggage, device cases, and the like.

In embodiments, the resonator may comprise switches that couple thepower and control circuitry into and out of the resonator circuit sothat the resonator may be configured only as a source resonator, only asa repeater resonator, or simultaneously or intermittently as anycombination of a source, device and repeater resonator. An exemplaryblock diagram of a circuit configuration capable of controlling andswitching a resonator between the three modes of operation is shown inFIG. 12. In this configuration a capacitively loaded conducting loop1208 is coupled to a tuning network 1228 to form a resonator. The tuningnetwork 1228 may be used to set, configure, or modify the resonantfrequency, impedance, resistance, and the like of the resonator. Theresonator may be coupled to a switching element 1202, comprising anynumber of solid state switches, relays, and the like, that may couple orconnect the resonator to either one of at least two circuitry branches,a device circuit branch 1204 or a source circuit branch 1206, or may beused to disconnect from any of the at least two circuit branches duringan inactive state or for certain repeater modes of operation. A devicecircuit branch 1204 may be used when the resonator is operating in arepeater or device mode. A device circuit branch 1204 may convertelectrical energy of the resonator to specific DC or AC voltagesrequired by a device, load, battery, and the like and may comprise animpedance matching network 1208, a rectifier 1210, DC to DC or DC to ACconverters 1212, and any devices, loads, or batteries requiring power1214. A device circuit branch may be active during a device mode ofoperation and/or during a repeater mode of operation. During a repeatermode of operation, a device circuit branch may be configured to drainsome power from the resonator to power or charge a load while theresonator is simultaneously repeating the oscillating magnetic fieldsfrom an external source to another resonator.

A source circuit branch 1206 may be used during repeater and/or sourcemode of operation of the resonator. A source circuit branch 1206 mayprovide oscillating electrical energy to drive the resonator to generateoscillating magnetic fields that may be used to wirelessly transferpower to other resonators. A source circuit branch may comprise a powersource 1222, which may be the same energy storage device such as abattery that is charged during a device mode operation of the resonator.A source circuit branch may comprise DC to AC or AC to AC converters1220 to convert the voltages of a power source to produce (usingoscillator 1224 and power amplifier 1218) oscillating voltages that maybe used to drive the resonator through an impedance matching network1216. A source circuit branch may be active during a source mode ofoperation and/or during a repeater mode of operation of the resonatorallowing wireless power transfer from the power source 1222 to otherresonators. During a repeater mode of operation, a source circuit branchmay be used to amplify or supplement power to the resonator. During arepeater mode of operation, the external magnetic field may be too weakto allow the repeater resonator to transfer or repeat a strong enoughfield to power or charge a device. The power from the power source 1222may be used to supplement the oscillating voltages induced in theresonator 1208 from the external magnetic field to generate a strongeroscillating magnetic field that may be sufficient to power or chargeother devices.

In some instances, both the device and source circuit branches may bedisconnected from the resonator. During a repeater mode of operation theresonator may be tuned to an appropriate fixed frequency and impedanceand may operate in a passive manner. That is, in a manner where thecomponent values in the capacitively loaded conducting loop and tuningnetwork are not actively controlled. In some embodiments, a devicecircuit branch may require activation and connection during a repeatermode of operation to power control and measurement circuitry used tomonitor, configure, and tune the resonator.

In embodiments, the power and control circuitry of a resonator enabledto operate in multiple modes may include a processor 1226 andmeasurement circuitry, such as analog to digital converters and thelike, in any of the components or sub-blocks of the circuitry, tomonitor the operating characteristics of the resonator and circuitry.The operating characteristics of the resonator may be interpreted andprocessed by the processor to tune or control parameters of the circuitsor to switch between modes of operation. Voltage, current, and powersensors in the resonator, for example, may be used to determine if theresonator is within a range of an external magnetic field, or if adevice is present, to determine which mode of operation and whichcircuit branch to activate.

It is to be understood that the exemplary embodiments described andshown having a repeater resonator were limited to a single repeaterresonator in the discussions to simplify the descriptions. All theexamples may be extended to having multiple devices or repeaterresonators with different active modes of operation.

Wirelessly Powered Audio Devices

Audio devices that have the ability to be powered and/or rechargedwirelessly may increase the utility and/or reliability of such devices.Wirelessly powered audio devices may provide important safety benefitsin many environments, such as industrial environments and airplaneenvironments as described above.

Audio devices, which may include headphones, headsets, speakers,portable speakers, hands free headsets, audio and video consoles, personworn heads-up displays, and the like, may be directly powered or may berecharged wirelessly. In this disclosure, embodiments and examples maybe described with relation to a specific audio device, or type ofdevice. It is to be understood that unless it is specifically statedotherwise, the techniques, designs, and methods described for a specificaudio device may be configured or adapted for other devices,environments, systems, and methods.

Device resonator structures, source resonator structures, repeaterresonator structures, power and control circuitry, and control methodsand algorithms described herein may be used by the systems, methods, anddevices configured for powering and/or recharging audio deviceswirelessly. In some embodiments, device resonators may be integrated orattached to the audio devices, the device resonators may be configuredwith device power and control circuitry to convert energy fromoscillating magnetic fields into electrical energy. The electricalenergy may be used to directly power the audio devices and/or rechargethe batteries of the audio device.

In some embodiments, audio devices may be configured to receive energyvia oscillating magnetic fields wirelessly from one or more sourceresonators. In some embodiments repeater resonators may be used in thedevices and system to improve the wireless energy transfer between theaudio device and the one or more source resonators.

FIG. 14 depicts a system with wirelessly powered headphones 1408 whichmay be powered and/or recharged wirelessly from source resonators and/orvia one or more repeater resonators. In the example system, headphones1408 that may be worn by a person 1406 may be integrated with one ormore device resonators 1412 and device power and control circuitry (notshown). The device resonators 1412 may be integrated into the cups ofthe headphones 1408, in the bridge of the headphones, and/or other partsthat may be sized and shaped to accommodate a resonator. In oneembodiment of the system, one or more source resonators 1416, 1418 maybe attached or integrated into the chair 1410 used by the user. One ormore source resonators 1416, 1418 may be integrated or attached to theheadrest, back rest, seat, and the like of the chair 1410. The sourceresonators may be coupled to source power and control circuitry and maybe powered from larger batteries, connected to outlet mains, or poweredby any energy sources and/or power supplied described in thisdisclosure.

In some embodiments of the system depicted in FIG. 14, one or more ofthe resonators 1416, 1418 attached or integrated into the seat may berepeater resonators. The repeater resonators may be sized, positioned,and configured to improve the coupling between one or more sourceresonators that may integrated or attached to the chair and/orpositioned near the chair and the device resonator(s). Source resonators1404, 1402 may be, for example, positioned or integrated into furniture,walls, ceilings, monitors, televisions, and other items. In an officeenvironment, for example, a source resonator may be attached orintegrated into a wall or a cubical panel next to the chair. The sourceresonator may be energized by energy from the mains. The sourceresonators 1402, 1404 may be directly coupled to the device resonators1412 of the headphones 1408 and/or couple via one or more repeaterresonators 1416, 1418 that may be near the headphones and/or integratedor attached to the chair 1410. Source resonators 1402, 1404 may bepositioned in front of the user, in back of the user, and/or above orbelow the user.

Different positions of source and repeater resonators may be appropriatefor different environments and use applications. In transportationapplications, such as airplanes, buses, cars, boats, and the like, forexample, a chair may stay in a fixed location relative to a vehicle andtherefore resonators that may be attached or integrated into the seatmay be source resonators as the resonators may be easily wired toreceive energy from the vehicles energy source.

In other embodiments, such as office environments and, for example,customer support centers or call centers, audio devices such asheadphones and telephone headsets may be worn by users sitting on mobileor movable chairs. Movable chairs may make it difficult or impracticalto integrate source resonators into the chair. In some embodiments,source resonators may be attached or embedded into stationary objectssuch as cubicle walls, for example, where power from the mains can beused to directly energize the source resonators. In some embodiments ofthe system, repeater resonators may be movable and configurable.Repeater resonators may be integrated or packaged such that they may beattached to walls, chairs, furniture, and the like to improve couplingto the device resonators in different environments. In an exemplaryembodiment, a chair or seat may itself be wirelessly powered via asource installed on a wall, floor, ceiling, furniture, and the like. Theenergy captured by a device in the chair or seat may be used to energizean element of the chair, such as a resistive component that may warm orheat the chair. In some embodiments, audio devices such as speakers maybe integrated into the chair or seat, such as in a theater or hometheater system, and may wirelessly receive energy from a sourceinstalled on a wall, floor, ceiling, and the like. In anotherembodiment, the energy captured by the device in the chair or seat mayin turn be used to wirelessly energize an audio device.

In some embodiments, the resonators attached or integrated into thechair or seat may be configured as multi-mode resonators that mayoperate as source, device, and/or repeater resonators. As describedherein, a resonator may be configured to operate with multiple modes. Aresonator that is attached to a non-stationary chair may in someinstances receive energy from an external source and store the energy inone or more rechargeable batteries that may be attached to the chair.The resonator may act as a repeater in some instances and may beconfigured to act as a source to power the audio device and may use theenergy from the batteries that were charged when the resonator wasoperating in device mode.

Resonators may be attached or integrated into different components orareas of an audio device. In the example of headphones, as depicted inFIG. 15, device resonators 1504, 1506 may be integrated into the cups1502 of the headphones. In other embodiments the device resonators andpower and control circuitry may be integrated or attached into otherelements of the audio devices such as the bridge of the headphones 1508.In some applications, integrating device resonators directly into theaudio device may result in a device resonator size or position that isnot practical for wireless energy transfer. In some embodiments a pod ordongle or enclosure that houses resonator structures and optionallydevice power and control circuitry may be remote from the audio deviceand the energy that is captured by the pod may be transferred to theaudio devices via a wired connection. In an exemplary embodiment, theheadphones may include a separate pod or dongle 1510 that may be wired1512 to the headphones. The pod may be detachable from the wire and/orthe headphones. In embodiments the pod or dongle 1510 may include one ormore device resonators and rechargeable batteries. Energy from theresonators of the pod may be used to recharge the batteries and/or powerthe headphones. The pod may be worn by the user and may be placed in apocket, backpack, or positioned for sufficient coupling and energytransfer from one or more source and/or repeater resonators. The pod1510 may in some embodiments include additional functionality such as amusic playback, radio reception and the like. In some embodiments thepod may be used to supplement, or instead of, the energy received by theresonators that may be integrated into the audio devices. For example,when the resonators that may be integrated into the cups of theheadphones are not able to receive or capture enough energy to power theheadphones, the pod may be attached to provide more energy.

In embodiments, various different resonators sizes, configurations, andtypes may be used. Capacitively loaded conducting loops, for example,may be integrated or wound into the cups of the headphones. In oneembodiment of the headphones, an oval shaped capacitively loadedconducting resonator coil is integrated into the cups of the headphones.The resonator coil, as depicted in an exemplary embodiment in FIG. 17,may be sized and shaped to fit inside the enclosure of the headphones.In some embodiments, the audio devices may include planar resonators,and use magnetic materials to improve coupling to the other resonatorsof the wireless power transfer system and/or to reduce loss.

Magnetic materials and/or highly conducting materials may be used toshield a resonator coil from lossy materials of the headphonecomponents. FIG. 16 shows an exploded view of a headphone with aresonator coil. Magnetic material 1606 comprising blocks, sheets,powder, and the like may be positioned between the resonator coil 1604and other electronics or lossy components that may be housed inside theheadphone cup 1608, which is connected to a headphone cord 1602. Themagnetic material 1606 may be shaped and sized to completely cover thelossy material of the headphones. In some embodiments the magneticmaterial may only cover specific components and may only partially coverthe lossy components and materials of the headphones. In someembodiments, the layer of magnetic material may be sized and shaped towrap around the resonator coil and may be larger than the resonatorcoil. In other embodiments the layer of magnetic material may be sizedto only cover specific regions or may be limited by weight, for example.

In addition to the layer of magnetic material, or instead of the layerof magnetic material, the device may include a layer of a goodelectrical conductor 1610 such as copper, aluminum, or the like. Thelayer of conductor y 1610 may be sized and shaped to cover lossyelements or materials of the headphones. In some embodiments the layerof conductor may be a different shape and size than the layer ofmagnetic material. In embodiments the layer of the conductor may belarger than the layer of magnetic material. In other embodiments thelayer of the conductor may only cover specific regions or areas.

In some embodiments, the position, orientation, and power transfercharacteristics of the resonators in the wireless energy transfer systemmay be designed to reduce or prevent interference with the audio outputof the device. Some audio devices may include a diaphragm and anactuator such as a voice coil or a solenoid coil that may be affected bythe presence of the magnetic fields of the wireless power system. Insome audio devices, the fidelity of the audio may be reduced or noisemay be introduced to the audio signals due to the magnetic fieldsinteracting with the actuators and/or other components of the audiodevice. In embodiments, the position, size, orientation, structure, andoperating characteristics or components used for wireless energytransfer may be designed and/or tuned to prevent interference with theaudio of the device.

In some embodiments, the frequency of the wireless energy transfer maybe selected to prevent or reduce interference with an audio signal. Inembodiments, the resonators may be tuned for frequencies above theaudible threshold of users and may be tuned to be above 22 kHz or more.In many embodiments the resonant frequency may be selected to besubstantially more than 22 kHz and may be as selected to be 200 kHz,2.26 MHz, 6.78 MHz, 13.56 MHz, or higher. The resonators and thecharacteristics of the wireless energy transfer systems may be tuned fora narrow operating frequency or a substantially single operatingfrequency such as to reduce or eliminate harmonics that may interferewith an audio signal. In embodiments the resonators may be configured toa frequency and characteristics such that harmonics or other signalsthat may fall within the audible frequency range or that may bedistorted to produce frequencies that fall within the audio band mayhave low enough energy component/density so as not interfere with theaudio signal at the audible frequencies.

Components that may be sensitive to interference from the magneticfields used for wireless energy transfer may be shielded and/or theresonators positioned to reduce the strength of the magnetic fields nearthe sensitive components. In one embodiment the audio device componentssuch as the speakers, voice coils, actuators, amplifiers, drivers, andthe like may be shielded from the magnetic fields using a layer ofmagnetic material and/or a layer of a good electrical conductor such ascopper, aluminum, and the like. The sensitive components may be covered,or partially covered by magnetic material and/or the electricalconductor to reduce or substantially eliminate the interaction with themagnetic fields.

In some embodiments, the one or more device resonators that areintegrated and/or attached to the audio device may be positioned and/ororiented to reduce the magnetic field strength near the sensitivecomponents. The one or more device resonators, for example, may bepositioned and oriented such that the sensitive components of the audiodevice minimally interfere with the one or more device resonators. Oneor more resonators may, for example, be positioned and oriented suchthat the dipole moment of the resonator is orthogonal to the dipolemoment of the audio device solenoid. In some embodiments the one or moredevice resonators may be positioned such that the sensitive componentsof the audio devices may be offset from the device resonators in aregion where the fields near the one or more device resonators arerelatively weaker than in other areas.

In some embodiments, wirelessly powered audio devices may include one ormore filters configured to filter noise at one or more operatingfrequencies or harmonics of the wireless energy transfer system. Thefilters may include tunable band-pass filters configured to filter noiseor interference due to the energy transfer. The attenuation, frequency,bandwidth, and the like of the filters may be adjustable based on theparameters of the wireless energy transfer. In some embodiments, thefrequencies used for energy transfer may change from one to anotherand/or may alternate between two or more frequencies. Filters of theaudio device may monitor the characteristics of the wireless energytransfer and adjust the filters accordingly. In some embodiments, theparameters of the wireless energy transfer may be received from thepower and control circuitry and the frequency response and/or theattenuation of the filters adjusted for these parameters.

In some embodiments, a wirelessly powered audio device may comprisenoise evaluation and/or monitor circuitry that may be used to generatecontrol and/or compensation signals to reduce any noise on the audiosignals that has been induced by the oscillating magnetic field used forpower exchange. The noise monitor signal may be configured to injectadditional signals onto the audio signal that may be used to reduce orcancel the noise induced by the oscillating fields of the wireless powersystem. In some embodiments, the noise evaluation and monitor circuitrymay control the audio signal reception circuitry in order tocharacterize and isolate induced noise signals from desired audiosignals. For example, the audio signal receptors may be at leasttemporarily, or at least intermittently, disconnected from the rest ofthe audio device circuitry so that a determination can be made as towhich signals are noise and which are the desired audio signals. Then,compensating signals may be added to the signal line of the audio deviceto reduce and/or cancel noise signals. The noise evaluation and/ormonitor circuitry may also be used to tune filters, control otherelectrical components, and control the power transmitted by the wirelesspower sources and repeaters as described in other sections of thisdisclosure.

The power demands of the audio devices may be continuously orperiodically monitored and the output power of any source resonatorsand/or repeater resonators of the system may be adjusted to provideadequate power to the audio devices while reducing the strength of thefields. In embodiments, the power output of the source resonators and/orrepeater resonators may be controlled to provide no more than 110% of120% of the required power to power the audio device.

FIG. 18 shows a block diagram of the components of an embodiment of anaudio device configured for wireless energy transfer. The wireless audiodevice 1800 may include speakers, microphones, and or other audio inputand/or output actuators or devices 1802. The speakers may be powered ordriven by one or more audio drivers 1808 that receive audio and datasignals from an internal or external source via a communication channel1804. The communication channel 1804 may be wired or wireless and mayuse Bluetooth, WiFi, or other wireless communication technologies andprotocols to receive data signals. In some embodiments the communicationchannel may use near field communications (NFC) and in some cases mayuse the same fields or components (i.e. resonators) that are used forwireless energy transfer. Energy that may be needed by the audio devicemay be received by one or more resonators 1812 that may be directlyattached/integrated to the audio device or separately wired. Theresonators 1812 may include one or more capacitively loaded loopresonators comprising wire or Litz wire, or printed circuit boards. Theresonant frequency of the resonators may be controlled by the power andcontrol circuitry 1810. The power and control circuitry may further beconfigured to provide impedance matching, rectification, and powercontrol. Energy from the power and control circuitry may be used toenergize the audio drivers, and other elements of the device. In someembodiments the audio device may include rechargeable batteries 1806.The rechargeable batteries 1806 may be recharged from energy received bythe resonators.

The wireless audio device may include a power demand monitor 1816. Thepower demand monitor 1816 may be used to monitor the power demands ofthe audio device and adjust the parameters of the wireless energytransfer to increase delivered power if insufficient power is deliveredor reduce the power if too much energy is delivered.

In some embodiments, the power demand monitor 1816 may monitor the powerdemand of the device and the power delivered to the device. Ifinsufficient power is delivered to the device, the power and demandmonitor may be configured to trigger an audio notification that may beused to alert the user to adjust the position or other parameters to theimprove the wireless energy transfer. The audio notification may includebeeps or other sounds to indicate to the user to reduce power usageand/or reposition any of the resonators in the system to improve theenergy transfer. The sounds may be used help the user establish theinitial configuration of the system, helping the user locate areasand/or positions of source and/or repeater resonators for sufficientenergy transfer. In some embodiments, the volume, frequency, and thelike of the audible indicators may be related to the field strength orpower received by the audio device. The audio device may in some casesbe configurable for a diagnostics or “setup” mode where the sounds ofthe audio device may be used to configure the orientations and locationsof source, repeater, and/or device resonators and components.

In some embodiments, a noise monitor 1814 may be used to monitor theinterference or noise on the audio output of the device. The noisemonitor may be configured to monitor the noise component on one or morefrequencies related to wireless energy transfer. The noise monitor mayinitiate a reduction in the wireless power of any sources and/orrepeaters of the wireless power system when the noise reaches athreshold. In some embodiments, when the noise reaches a threshold, oneor more filters may be activated. The filters may be bandpass filters atthe frequency of the noise component to attenuate the noise. In someembodiments, a noise monitor may initiate active noise cancellation.This may include circuitry to create a signal with phase and amplitudedesigned to cancel the noise signal. For example, for noise ofsinusoidal nature, a cancellation signal or signals may be created withthe same amplitude but with phase that is 180 degrees out of phase withthe noise signal for destructive interference. In further embodiments,noise cancellation may include circuitry to remove linear and non-lineardistortion in an audio signal. Distortion in an audio signal mayoriginate externally to the audio device or internally, such as from theelectronics of audio device. The wireless energy transfer system mayalso induce linear and/or non-linear distortion in the audio signal.Removing distortion may include circuitry to restore the amplitude andphase of an audio signal and/or remove distorting harmonics orinteracting frequencies. The noise monitor may activate circuits orother electronics to remove such distortion.

FIG. 19 depicts a method 1900 for controlling the energy transfer for anaudio device. In block 1902, the wireless energy transfer may beinitiated by a source and/or repeater resonator. In block 1904, thepower demand monitor may monitor the power demands of the audio device.In block 1906, the noise monitor may monitor the noise component in theaudio signal. In some embodiments, if a noise component is detected, inblock 1908 the audio device may signal the source to turn down theoutput power to a lowest level that still satisfies the power demands ofthe audio device. In another embodiment, if a noise component isdetected, the audio device may change a resonant frequency at which thewireless energy transfer is operating and/or a resonant frequency of adevice or source resonator. In yet another embodiment, if a noisecomponent is detected, the audio device may change the dipole moment ofa resonator. In block 1910, if noise is still present in the audiosignal, filtering of the noise component may be initiated with bandpassfilters tuned to filter the frequencies associated with wireless energytransfer.

Wireless energy transfer may be used to directly power the audio devicesand/or recharge the batteries when in normal use by a user (i.e. sittingin a chair). In some embodiments wireless energy transfer may be used toalso recharge the batteries of the audio devices when they are not inuse, when the audio devices are placed on a desk, charging pad, carryingcase, and the like. In embodiments a wireless energy source may beintegrated to a pad, a desk, a stand, a carrying case, and the like. Thesource may wirelessly transfer power to the resonators of the devicewhen the audio device is placed on or near the source. In oneembodiment, as depicted in FIG. 20, a source resonator may be integratedor attached to pad 2002 or a carrying case. Device resonators 2004, 2008integrated or attached to the headphones 2006 may receive energy fromthe source and recharge the batteries of the headphones.

Device resonators may be integrated or attached to other audio devicessuch as a headset depicted in FIG. 21. A headset 2102 may be integratedwith a device resonator 2104 and power and control circuitry configuredto recharge a battery. When the device resonator is positioned close toa source and/or repeater resonator, the device resonator may rechargethe internal battery of the device. In one embodiment, as depicted inFIG. 22, a headset 2208 may be charged in cup shaped container 2202 thathas a source resonator 2206 attached to the bottom or sides 2204 of thecontainer 2202. The cup shaped container may be used in cup holders in avehicle or seat, for example. In some embodiments, one or more repeaterresonators may be installed into the cup shaped container to deliverwireless energy to the audio devices in the container. In the example ofa vehicle, one or more source resonators may be located in thedashboard, center console, side panels, seats, ceiling, and the like ofa vehicle and may wirelessly deliver energy to multiple cup shapedcontainers or other devices within the vehicle.

In one example embodiment of the configuration depicted in FIG. 14,headphones 1408 are integrated with a device resonator 1412. The deviceresonator coil is wrapped around one of the ear cups and comprises 8turns of Litz wire formed around a 9 cm by 7 cm ear cup. The power andcontrol electronics are positioned inside the cavity of the headphones.The energy captured by the resonator is converted to DC current by thepower and control circuitry and used to power the electronics of theheadphones (i.e. noise cancellation circuitry) and also optionally tocharge the battery of the headphones. A repeater resonator 1416 ispositioned near the headphones. The repeater resonator is shaped to fitaround the perimeter of the headrest 1414 of a chair 1410. The repeaterresonator is positioned to improve the coupling between a sourceresonator 1402, positioned behind the chair, and the smaller resonatorcoil 1412 in the headphones 1408. The repeater resonator 1416 comprises8 turns of Litz wire forming a 30 cm by 17 cm rectangular shape. Theshape and materials of the repeater resonator may be chosen for a 250kHz operating frequency. In other embodiments the materials and shape ofthe resonator may be chosen based on the system operating frequency.

A source resonator 1402 comprising six turns of Litz wire wound in a 63cm by 83 cm enclosure is positioned behind the chair. The sourceresonator is coupled to an amplifier which drives the resonator with anoscillating current at 250 kHz. In other embodiments the sourceresonator and amplifier may be optimized or designed for otherfrequencies, for example, 1 MHz, 2.26 MHz, 6.78 MHz, 13.56 MHz, and thelike. For embodiments with other frequencies, the resonator coil maycomprise different construction such as a solid wire, etched conductoron a printed circuit board, and the like. The example embodiment of thesystem depicted in FIG. 14 comprising the source 1402, repeaterresonator 1416 and the headphones 1408 delivers about 100 mW of power tothe headphones over a distance 1420 of 90 cm. The operation of theheadphones (i.e. sound quality, noise cancellation) was not affected bythe fields of the wireless energy transfer.

In one embodiment of the configuration shown in FIG. 22, wirelessearphones 2208 are charged wirelessly in a cup like container 2202. Theearphones have a rechargeable battery and a small resonator 2210 as wellas power and control circuitry. The earpiece 2208 is configured toreceive 0.35 W of power from the device resonator 2210 integrated intothe earpiece. The earphones receive energy from a pad like surface witha circular coil. The system is configured to operate at 6.78 MHz. Thesource resonator 2206 that is integrated into a cup is capable ofrecharging multiple earphones simultaneously. The earphones will chargein any orientation with an offset or spacing of up to 6 mm from thesource. An exemplary embodiment of the device resonator coil is depictedin FIG. 23 and an exemplary embodiment of the source resonator coiltrace is shown in FIG. 24. Both coils are printed on a printed circuitboard and designed to operate at 6.78 MHz.

In one example embodiment of the charging configuration shown in FIG.20, a noise cancelling headphone is configured to be charged from aheadphone case or a pad. A wireless energy source is embedded in theheadphone pad 2002. The headphones have an integrated resonator 2004 inone of the ear cups. The resonator coil comprises 8 turns of Litz wireforming a 9 cm by 7 cm ellipse. The Litz wire is covered with tiles ofmagnetic material to shield the resonator from the electronics of theheadphones. When the headphones are placed on the pad 2002 theheadphones can charge. The headphones can receive 0.1 W of power or morefrom the source.

Another type of audio device whose performance may be improved and/orenhanced by wireless power transfer capabilities is a hearing aid. Awirelessly powered or charged hearing aid may be self-contained with nowired connections between the hearing aid and the source of power. Awirelessly charged hearing aid may comprise a resonator and/or battery.The battery may be a wirelessly chargeable battery. A wirelesslychargeable battery may be self-contained with no wired connectionsbetween the battery and the source of power.

FIG. 25 shows an exemplary embodiment of a wirelessly powered hearingaid system. The hearing aid may comprise a resonator and battery andelectronics. The hearing aid may comprise a resonator that may receivepower from a wireless energy source. The power received from thewireless energy source may be used to charge a battery encased in thehearing aid. The battery may be a wirelessly chargeable battery. Thewireless energy source may comprise a resonator 2502 and electronics.The wireless source may be coupled to a power supply 2503 such as ACmains, a battery, a solar panel, a generator, and like. The wirelesspower transfer system may also comprise multiple source resonators,multiple devices resonators and one or more repeater resonators. Theseresonators may be arranged to make the wireless recharging of thehearing aid batteries more convenient, more reliable, more energyefficient and the like.

In some embodiments, a single wireless power source may transfer powerto at least one wirelessly powered hearing aid and may transfer power totwo, or more than two, wirelessly powered hearing aids. The wirelesspower source may deliver power to the hearing aids in any relativeorientation to each other.

FIG. 26 shows an exemplary embodiment of the resonators on both thedevice and source side of the wirelessly powered hearing aid system. Inpreferred embodiments, the source (2501) may comprise a PCB type coil(2601) and a FJ3 type ferrite (2602). In an exemplary embodiment, thesource coil has 4 turns. The hearing aid or device (2501) may comprise aPCB type coil (2603) and FJ3 type ferrite (2604) and a highly conductingmetal shield (2605). In the exemplary embodiment, a device coil may have10 turns of a conducting material. The wirelessly powered hearing aidsystem may couple at a frequency of 6.78 MHz or 13.56 MHz. Inembodiments, the device resonator coil may need to be very small so thatit can be integrated in the hearing aid. Printed circuit boardresonators, potentially made on flexible substrates, may be preferredembodiments for applications where the device receiving wireless poweris very small. In such embodiments, the resonant frequency of themagnetic resonators may be designed to be higher than 1 MHz. At higherfrequencies, the inductive elements of the resonators may be realizedusing printed circuit board technology. The capacitive elements of theresonator may be realized using smaller chip capacitors. The capacitiveelements may also be realized using capacitive structures integratedusing circuit board technology.

In embodiments, a source designed specifically for recharging hearingaids on a pad, in a bowl, in a region, and the like, may be designed tohave a power output level between 10 mW, 100 mW and/or 1 W. The distancebetween the source and hearing aid may be 5 mm. In an exemplaryembodiment, the range of coupling factors, k, may be between 0.01 and0.1.

FIG. 27 shows an exemplary embodiment of the wirelessly powered hearingaid system. The hearing aid may comprise a wirelessly chargeablebattery. The wirelessly chargeable battery may comprise a resonator andelectronics. The battery's electronics may include an impedance matchingnetwork and a rectifier.

In some embodiments the wirelessly powered hearing aid system maycomprise a source that can charge multiple batteries at any time.

FIGS. 28A-B show efficiency predictions for an exemplary embodiment ofthe wirelessly powered hearing aid system. FIG. 28A shows the calculatedcoil-to-coil efficiency between a wireless power source and a hearingaid device as the size of the source coil is varied from 20 to 40 mm.FIG. 28B shows the calculated coupling coefficient of the system as thesize of the source coil is varied from 20 to 40 mm.

In other embodiments, the wirelessly chargeable hearing aid system mayconsist of more than one separately encased parts. Each of these encasedparts may comprise a resonator, electronics, and a battery. In someembodiments, one of the encased parts may act as a passive resonator orrepeater that may couple to both the source and the resonators in theother encased parts of the hearing aid. In some embodiments, someencased parts of the hearing aid system may be implanted inside theuser's body. In some embodiments, the passive resonator or repeater maybe formed to fit over or around the inside or outside of the ear.

In other embodiments, the wirelessly chargeable hearing aid system maycomprise implants such as middle-ear implants or cochlear implants. Theuser may wear the electronics and/or wirelessly charged batterycomponents elsewhere on their body.

In other embodiments, the wireless power source may be encased in a cupor box shape. This cup or box may be shaped to hold a single hearing aidor two hearing aids or more than two hearing aids.

In other embodiments, the wirelessly powered hearing aid may be chargedwhile worn by the user. The wireless power source may be integrated intothe back of a chair or clothing such as a hat so that the hearing aidmay be charged while worn by the user. In embodiments, source and/orrepeater resonators may be integrated into a structure that resemblesover-the-ear head phones, ear muffs or ear warmers. In otherembodiments, source and/or repeater resonators may be integrated intohats, caps, scarves, shoulder pads, clothing, and the like, and may beused to charge or power the hearing aids while a person is using them.In embodiments, hearing aids may be powered and/or recharged by the samesources and or repeaters used to power or recharge other audio devices.In embodiments, in-use hearing aid recharging and/or powering systemsmay preferably comprise at least one repeater resonator.

In embodiments where the hearing aids are being powered directly from awireless power system, the control, filtering and noise cancellationtechniques described for headphones may also be applied to the hearingaids.

In embodiments, recharging of headphones, ear-buds, hearing aids and thelike may be accomplished using portable wireless power sources. Forexample, a wireless power source may receive power from a portablebattery that may be stored in a briefcase, a back pack, a hand-bag, apurse, a pocket, a glove compartment, luggage, and the like, and theaudio devices may be recharged by placing, dropping, depositing, and thelike, them into the briefcase, back pack, hand-bag, purse, pocket, glovecompartment, luggage and the like.

It is to be understood that although a specific set of audio devices andenvironments was used illustrate the devices and methods, thetechniques, systems, and devices may be used in a large number ofdifferent audio devices and environments. System, devices, and methodmay be adapted to industrial environments, for example, where noisecancelling headphones may be recharged or powered wirelessly.Transportation, entertainment, and other venues may also employ thetechniques.

Unless otherwise indicated, this disclosure uses the terms wirelessenergy transfer, wireless power transfer, wireless power transmission,and the like, interchangeably. Those skilled in the art will understandthat a variety of system architectures may be supported by the widerange of wireless system designs and functionalities described in thisapplication.

This disclosure references certain individual circuit components andelements such as capacitors, inductors, resistors, diodes, transformers,switches and the like; combinations of these elements as networks,topologies, circuits, and the like; and objects that have inherentcharacteristics such as “self-resonant” objects with capacitance orinductance distributed (or partially distributed, as opposed to solelylumped) throughout the entire object. It would be understood by one ofordinary skill in the art that adjusting and controlling variablecomponents within a circuit or network may adjust the performance ofthat circuit or network and that those adjustments may be describedgenerally as tuning, adjusting, matching, correcting, and the like.Other methods to tune or adjust the operating point of the wirelesspower transfer system may be used alone, or in addition to adjustingtunable components such as inductors and capacitors, or banks ofinductors and capacitors. Those skilled in the art will recognize that aparticular topology discussed in this disclosure can be implemented in avariety of other ways.

Unless otherwise defined, all technical and scientific terms used hereinhave the same meaning as commonly understood by one of ordinary skill inthe art to which this disclosure belongs. In case of conflict withpublications, patent applications, patents, and other referencesmentioned or incorporated herein by reference, the presentspecification, including definitions, will control.

While the invention has been described in connection with certainpreferred embodiments, other embodiments will be understood by one ofordinary skill in the art and are intended to fall within the scope ofthis disclosure, which is to be interpreted in the broadest senseallowable by law. For example, designs, methods, configurations ofcomponents, etc. related to transmitting wireless power have beendescribed above along with various specific applications and examplesthereof. Those skilled in the art will appreciate where the designs,components, configurations or components described herein can be used incombination, or interchangeably, and that the above description does notlimit such interchangeability or combination of components to only thatwhich is described herein.

All documents referenced herein are hereby incorporated by reference.

We claim:
 1. A wirelessly powered audio device comprising: an audiooutput element adapted to generate sounds audible to a user; a deviceresonator structure adapted to wirelessly receive energy via oscillatingmagnetic fields, the device resonator configured to reduce theinteraction of the magnetic fields with the audio output element; and apower demand monitor adapted to monitor the power demands of the audiodevice and the power received via the device resonator structure, thepower demand monitor further configured to cause the audio outputelement to generate an audible signal when the power demands of theaudio device exceed the power delivered by the device resonator.
 2. Theaudio device of claim 1, wherein the device resonator structure ispositioned near the audio output element such that the audio deviceperformance is minimally affected by the presence of the deviceresonator.
 3. The audio device of claim 2, wherein the audio outputelement comprises a solenoid coil and wherein the resonator ispositioned such that the dipole moment of the resonator structure issubstantially orthogonal to the axis of the solenoid.
 4. The audiodevice of claim 1, further comprising magnetic material, wherein themagnetic material is positioned to shield the audio output element fromthe magnetic fields near the device resonator structure.
 5. The audiodevice of claim 1, further comprising a sheet of good electricalconducting material, wherein the sheet of good electrical conductingmaterial is positioned to shield the audio output element from themagnetic fields near the device resonator structure.
 6. The audio deviceof claim 1, further comprising rechargeable batteries, wherein energycaptured by the device resonator is at least in part used to rechargethe batteries.
 7. The audio device of claim 1, wherein the deviceresonator structure comprises capacitively loaded conducting loopsprinted on a substrate.
 8. The audio device of claim 1, wherein thedevice resonators are integrated in a pod that is wired to the audiodevice.
 9. The audio device of claim 1, wherein the audio devicecomprises one or more speakers.
 10. The audio device of claim 1, whereinthe audio device is a headset.
 11. The audio device of claim 1, whereinthe audio device is configured to wirelessly receive energy from asource or repeater resonator in a chair.
 12. The audio device of claim1, wherein the audio device is a hearing aid.
 13. A wirelessly poweredheadphones, the headphones comprising: a speaker element comprising adiaphragm and an actuator; a device resonator structure adapted towirelessly receive energy via oscillating magnetic fields, the deviceresonator configured to reduce the interaction of the magnetic fieldswith the speaker element; and a power demand monitor adapted to monitorthe power demands of the headphones and the power received via thedevice resonator structure, the power demand monitor further configuredto cause the speaker element to generate an audible signal when thepower demands of the headphones exceed the power delivered by the deviceresonator.
 14. The headphones of claim 13, wherein the speaker elementis positioned for minimal performance degradation by the deviceresonator structure.
 15. The headphones of claim 13, further comprisingmagnetic material, wherein the magnetic material is positioned to shieldthe speaker element from the magnetic fields near the device resonatorstructure.
 16. The headphones of claim 13, further comprising a sheet ofgood electrical conducting material, wherein the sheet of goodelectrical conducting material is positioned to shield the speakerelement from the magnetic fields near the device resonator structure.17. The headphones of claim 13, wherein the headphones are configured towirelessly receive energy from a source or repeater resonator in achair.
 18. The headphones of claim 13, further comprising rechargeablebatteries, wherein energy captured by the device resonator structure isat least in part used to recharge the batteries.
 19. The headphones ofclaim 18, wherein the headphones are configured to be wirelesslyrecharged from a source resonator embedded in a carrying case.
 20. Amethod for wirelessly powering of an audio device, the methodcomprising: initiating wireless energy transfer from a wireless energysource; monitoring, using a power demand monitor, a power demand of theaudio device; monitoring, using a noise monitor, the noise of an audiosignal due to the wireless energy transfer; adjusting energy transfer toa minimum level that satisfies the power demand of the audio device; andfiltering a noise component from the audio signal.